I wanted to document my efforts in fixing up a 1997 Volvo 850 wagon to help my three children understand and appreciate what it takes to get an older car fully functional and running reliably. They may be doing something like this for themselves in the future, so this blog is for their reference. If it helps other Volvo 850 owners along the way, all the better.

Parts and labor at most shops–Volvo dealers in particular–are very costly. This effort approaches reasonable economy if you do it yourself (DIY), so most everything shown was done at home where labor is free. Cost of parts is given at the end of each task.

Postings are presented in order of task performed with most recent at top. Seemingly random, I did these tasks as time, parts and weather permitted and issues were observed. Previous owners had some work done already so I did not need to tackle those items which might seem more urgent (brakes, tires, struts).

Note: This is not a step-by-step repair document. It shows only the basic task accomplished. There are plenty of internet repair forums for this. However, many posts are detailed and somewhat educational (explanation of what/why/how). I don’t pretend to be an expert or authority on Volvos; this blog is just sharing my experience and opinions with my kids and other readers.

I’ve had these sub-frame bushing inserts laying around for months before I finally got around to installing them. IPD has several unique Volvo 850 products that are really good and this is one of them.

IPD sub-frame bushing kit includes four PU inserts, two syringes of lubricant and one small tube of thread locking compound.

The general idea is that these inserts tighten up the engine sub-frame mounting bushings that degrade over time. Users have reported a big improvement in steering and handling in general.

Polyurethane (PU) insert tightens up existing sub-frame bushing.

850 engines sit on a separate sub-frame which is then connected to the car chassis via mounting bushings on four corners. These bushings are made of rubber and give some of the same vibration isolation that the main engine mounts do. Over time rubber degrades and depending on mileage, driving conditions and chemical exposure these sub-frame mounts can get really sloppy. The whole engine sub-frame can move front to back and side to side a little compared to new bushings. Symptoms of worn bushings include clunking noise, uneven tire wear, steering play/movement and steering influenced when accelerating or braking.

Replacing the mounts is both expensive and time-consuming. IPD came up with this reasonably priced solution that takes only an hour or two to install. They fill in the gaps of the original bushings to tighten them up and give a factory-new feel.

Start by lifting the front of the car. This can be done with wheels on so this is a good time for ramps. You work on the four bushings one at a time so that the sub-frame doesn’t need extra support. I started with the front right as shown. The process is presented below.

Driving the car up on ramps gives good access to the front bushings and adequate room for the rear. Don’t forget to chock the rear wheels.

Front bushings tackled first.

Large, long bolt removed. Bushings now viewed clearly.

Half of the lube per syringe is squirted into the voids where the inserts will be placed.

Insert pressed into place in bushing. In this case the bushings were in good condition and I had to hammer them in with a rubber mallet.

New bolts are recommended for reattachment but this is not always practical. IPD provides a small amount of thread locking adhesive for more security when the original bolts are re-used.

Original bolt secured to torque specification with thread locking adhesive. One front corner complete. Repeat for other side.

For the front bushings I found that the engine dropped a bit too much so supported the sub-frame with a floor jack. This was not necessary for the rear bushings.

Rear bushings treated the same way with an additional step of unbolting the triangle-shaped frame plate from the chassis.

After installing the inserts on all four corners I drove the car off the ramps and took it for a test drive to see if things had changed. There is a slight improvement in steering feel/play but nothing dramatic. In the case of this project car the original bushings were in surprisingly good shape after 18 years. In fact, I had a hard time pressing the inserts into the bushings which indicated the rubber was still fairly intact and strong, plus we had no significant issues with steering or vibration. Surely there are many older 850s out there with really worn bushings because there are a lot people who report a big improvement after installing these. I don’t regret doing this job on this car because it is preventive maintenance so we shouldn’t need to deal with these in the future.

IPD recommends checking front end alignment when sub-frame bushings are worked on as the steering gear/rack might have moved a small amount.

The last thing I looked into while the car was home this past weekend is a rattling noise under the car. It happened only when the car was in drive (automatic transmission) and the brakes were applied.

This symptom told me the problem was related to the slight shift in engine rotation when the car is in drive. Reference post #105 to learn how the engine tilts to the back when in drive and the car is not moving.

Because the rattle is not heard when the transmission is in reverse, park or neutral, it also means that it is a very slight amount of engine rotation that causes metal-to-metal contact.

So I went looking for possible exhaust contact points under the car with the front up on ramps.

I spotted a heat shield just under the pipe connecting the exhaust manifold to the catalytic converter.

This shield is clipped onto a round tube and then lightly secured in one corner with a screw. The sheet metal is very flexible so the shield can move quite a bit, rotating on the clips. Apparently I bumped it up towards the exhaust pipe while working under there recently. Or perhaps the daughter drove over something that pushed it up.

On a side note to the previous post where we discussed how important the Mass Air Flow (MAF) sensor is, I want to bring up the topic of K&N brand air filters.

K&N makes a unique type of air filter that has a fine mesh screen that is saturated with oil. The oil is supposed to trap dust and debris but also let more air flow through. Some automotive enthusiasts swear by K&N because they reportedly increase engine horsepower. Another benefit is that they can be cleaned and re-oiled so long-term cost is less than replacement filters.

In the case of these normally aspirated (non-turbo) 850 engines, there is no apparent increase in horsepower, at least in my experience.

The downside to the K&N filter is that because it is oiled, some of that oil will leave the filter and pass on to the intake manifold. Immediately after the filter is the MAF sensor and it is reasonable to assume that some oil will end up on the sensor. This would affect heat transfer and sensor accuracy.

With these two facts in mind, I opted to remove the K&N air filter from our 850 sedan and replace with a standard filter.

Removed and discarded K&N filter.

Installed new standard Wix filter.

Air cleaner cover had alert stickers advising any service personnel that the air filter could be renewed instead of being replaced.

Removed K&N stickers from the air cleaner cover.

I welcome feedback in the comments from any readers who have more experience with K&N filters, pro or con.

Summary: Mass air flow (MAF) sensor was misbehaving so it was cleaned along with sensor electrical connector contacts. Also observed that the preheat air valve was stuck in preheat position so MAF was always seeing hot air. Solved this problem by mechanically fixing defective air control valve in the position for fresh air only.

Details: Along with the engine coolant temperature (ECT) sensor, the mass air flow (MAF) sensor is one of the two most critical sensors for Volvo 850 (and most other cars) engine operation. Either being defective can cause the engine to run rough or not run at all and both affect fuel economy as well.

We had an incident a few weeks back where this project car was running very roughly. I fiddled with the MAF sensor connector which is located next to the air cleaner housing and the engine started running smoothly again. That told me there was an issue with the sensor or its electrical connection.

While the car was home this weekend I tore into the air cleaner to get to the MAF sensor and gave it a good cleaning. Debris or dirt on the sensor elements can significantly affect the air flow reading and sometimes just a few taps will dislodge particles. This may have been what happened when I wiggled the connector to restore smooth engine idle.

Cleaning of the MAF sensor is best done by removing the sensor from its housing. However, on this car the screws from the factory require an unusual 5-point Torx security bit, which I don’t have. Interestingly, our other 1997 model 850 has 6-point security screws which I can remove, so Volvo is inconsistent here.

This car had 5-point Torx security screw head for the MAF and I don’t have the tool for this…

…so I removed the whole MAF assembly for cleaning.

So I sprayed MAF cleaner with the sensor still installed in the housing. The sensor elements are very fragile and should never be touched or disturbed. This is an expensive part to replace.

Cleaned MAF sensor with special spray. Other cleaners may leave residue which can harm or alter sensor reading.

Spray MAF sensor cleaner on and around the sensor elements.

Make sure the laminar flow grid is also clean because air flows towards the sensor from this side.

While I had the air intake and filter housing dissasembled, I checked the preheated air valve for proper operation. This may be unique to North American 850s because of emissions requirements; I don’t know if this is a feature elsewhere.

There is a flapper valve under the air filter which selects between ambient air and preheated air (passes over exhaust manifold), or a mix of both, depending on air temperature. On older 850s there is a thermostat that moves a rod to operate the air valve directly. This is a known common failure item. On late-model 850s and early V70s there is a thermostat in the air cleaner housing that modulates a vacuum valve to regulate the air valve in conjunction with a mechanical thermostat.

Access to the preheat air valve requires removal of air cleaner housing. Valve can be seen hanging below the air cleaner

Preheated air valve unclipped from air cleaner housing, on the right. Fresh air intake is at bottom, pre-heated intake far right, outlet at top.

On this car the air valve was stuck in the heated air position only, even with strong vacuum. This means that the MAF sensor has been getting pre-heated air all the time. The sensor reading will be affected by this and also may be damaged by constant flow of hot air.

Air valve always stuck in this position, blocking fresh air and open to pre-heated air.

Took apart the valve assembly to see if I could replace the thermostat and to get a better look at the vacuum valve part. It gave me a good idea how it works but I quickly realized it was broken.

Preheat air valve disassembled.

I applied a vacuum directly to the vacuum valve and could see the piston moving up and down as designed.

Piston extended with no vacuum. Would select preheated air.

Piston retracted with hard vacuum. Would pull air valve to cold air inlet.

So the vacuum valve itself seems to be working but when the flapper is connected to the piston and the whole thing reassembled, it doesn’t move. When I apply vacuum the piston does retract but the plastic connector to the flapper pulls around the thermostat and the flapper stays in preheat position.

Vacuum valve pulls piston down but plastic coupling stays up and valve stays in preheat position.

There is clearly a different result when the flapper is attached. I surmise that the plastic rim that pulls in was worn out and so it just slips around the thermostat when the vacuum valve pulls it in. If the hole in the plastic were smaller it should pull the whole thermostat (metal rod) down as it does without the flapper attached. So a proper fix would be to replace this vacuum valve assembly.

If this were the older preheat valve design it would be a simple part (thermostat) to swap out. Unfortunately I can find no parts information on the vacuum-operated valve for this car (both of our 1997 850s have the late design). It’s not mentioned in the usual parts places (FCP, IPD, Volvopartswebstore.) The only mention of it is on the AllDataDIY site without parts info.

I suppose I could go to a Volvo dealer parts department and ask them to chase it down but we know how expensive that would be. After reading the functional description of the design, I decided that we really don’t need the preheat feature here in central Texas where it rarely gets below freezing. With 9-10 months of the year in a warm climate, the preheat valve should be open to cool air almost all the time, and there is no real consequence to not having preheated air. So I rigged it to stay open to fresh air at all times, blocking the preheated air.

This was accomplished by drilling a hole in the flapper valve and using a long 2″ machine screw with a jam nut to keep it open.

Air valve held open to fresh air (closed to preheated air) with long screw and jam nut.

In addition to preserving the life and functionality of the MAF, we hope to gain a little power out of this mod. Other people with stuck air valves have reported an increase in power when they defeated the preheat intake. I expect this is because the fresh air intake has a slightly larger cross-sectional area than the preheated hose so more air can get to the intake manifold. Cooler air may also give a more accurate reading of air flow with the MAF as its principle of operation is to measure heat transfer in the sensor. More accurate air flow measurement should give a better fuel/air ratio, resulting in more efficiency (better fuel economy?) and power.

Reassembled the air cleaner and reconnected everything else. Also sprayed electrical contact cleaner on MAF sensor pins and sockets and mated/unmated a few times to wipe off oxide and prevent future intermittent connections.

Car runs fine now and time will tell how well the engine runs with this modification.

$0- no cost, using supplies and parts laying around.

Technical Notes: The “new control method for preheating air” is described in the Technical Service Bulletin 2-25-818, excerpts given here:

The system controls the intake air temperature so that it remains between +27°C (81°F) and +37°C (99°F) in the 850.

Function

The intake manifold vacuum in the plastic tubes is distributed from the multi-nipple (1) via a bimetal sensor-controlled damper (2) to a vacuum tank (3) which controls a damper, which opens and lets hot air into the cold intake air. When the throttle is wide open no vacuum is created and the air damper remains closed.

When the outside temperature is cold and with wide open throttle (WOT), the center damper is held open by a wax thermostat (4), which is located between the vacuum tank and the center damper.

You can tell if the car has the new control scheme by the presence of two vacuum ports on the rear of the air cleaner cover.

Preheat air vacuum control thermostat on back of air cleaner cover with inlet and outlet tubing nipples shown.

Inside of air cleaner cover showing vacuum control thermostat.

Regarding the MAF, excerpts of the description and operation are given below:

The Mass Air Flow (MAF ) Sensor supplies the Engine Control Module (ECM ) with a signal describing the intake air mass.

This information is used to calculate:

Injection period

Ignition timing

If the engine coolant fan needs to run-on.

The mass air flow (MAF) sensor consists of a plastic housing containing a connector, electronic circuitry and an aluminum heat sink. The mass airflow (MAF) sensor measuring device is a heated film mounted in a pipe which is cooled by the intake air to the engine. The heated film consists of four resistors:

The mass air flow (MAF) sensor is supplied with battery voltage and has separate power and signal ground points. The signal from the sensor varies from 0 V to 5 V depending on the mass of air passing. Voltage increases with air flow.

Since working temperature is relatively high (170°C ), and the flow and temperature sensitive resistors are mounted on the side of the hot film, a burn-off function is not required.

The engine control module (ECM) will adopt substitute values if the mass air flow (MAF) sensor signal is missing or faulty.

The mass air flow (MAF) sensor is located between the Air Cleaner (ACL ) cover and the fresh air intake.

One other complaint arrived with the car for the long weekend that involved the remote door lock/unlock feature that I retrofitted back in task #90.

When keyless entry was installed on this car it came with an old, used remote transmitter (key fob) with an aged battery inside. Turns out the two coin cells inside were running low and the remote would work only in close proximity to the car.

Installed two fresh coin cells and now the remote transmitter works just fine.

Two things I learned while playing with the key fob: First, the transmitter chirps once when the lock or unlock button is pressed and the batteries are fresh. When the coin cells are low the key fob chirps three times when a button is pressed. So that is one clue that the batteries need to be replaced.

Transmitter chirps only once upon button push if batteries are fresh; more chirps indicates low battery charge.

The other thing I learned (actually, I knew this, but was reminded) is that lithium coin cells will test fine on a voltmeter even when they are fairly discharged. Their chemistry still provides nearly full voltage with no load as when measured with a modern digital multimeter (DMM).

Battery charge is low even though both (2x3V lithium cell) read 6VDC with no load.

So to properly check the coin cells you need a special load tester to measure actual battery capacity. Since few of us have such a thing, my suggestion is to listen to the key fob and replace batteries when you hear more than one chirp.

With fresh batteries the transmitter chirps only once and the doors can be locked/unlocked from a practical distance.

One other thought here on this topic– Sometimes the key fob transmitters go bad. Even with fresh batteries they may not work. If you suspect the remote is bad, you need to check for radio frequency (RF) signal being transmitted. Some auto parts stores have a tester at the counter. One other way to check at home is use your own RF sniffer. I have this cheap one from Harbor Freight Tools that detects RF signals. When you push the lock and unlock buttons, the tester will flicker and chirp to indicate a signal.

RF sniffer indicates that the remote is transmitting a signal when a button is pushed.

The car has come home from college for our Thanksgiving holiday and I got to work on a few things.

First up is the front right engine mount. Daughter complained about vibration and I have replaced the other two engine pads already along with the upper and lower torque mounts so this is the last of the engine mounts to tackle.

The front right engine mount is the smallest of the three mounts and is located in the front right side of the car. It is actually on the front left side of the transverse-mounted engine and is sometimes referred as front left. At any rate, it is known to fail frequently and sooner than the others and it is the only one I have not replaced yet. Visual exam showed no issues but I thought I should replace it based on time and mileage.

Starting point is with the front of the car lifted up securely on jackstands with the front right wheel off. The wheel well flap is also folded back and secured to access the lower front of the engine.

Right front engine mount is visible just below and to the left of the crankshaft pulley (below red handle clamp).

Before removing the mount I measured the distance from the bottom of the oil pan to the top of the sub-frame for reference. It was right around 3/8″ (9.5mm), just enough for me to stick my pinky finger in the gap.

Measured 3/8″ gap between oil pan and sub-frame…

…which is just enough for me to stick my pinky finger in the gap.

Removal of the mount involves unscrewing the two bolts to the engine (horizontal) and then two bolts to the sub-frame (vertical). The three bolts on the right are easy to remove. The one on the left requires swivel adapters and a short socket wrench to remove because it’s surrounded on all sides.

Two bolts to engine removed and two to sub-frame to free the mount.

Once the engine mount is unbolted we lift the engine up slightly with a floor jack under the oil pan with a block of wood as a cushion and to spread the load around.

Lift engine off mount slightly.

The mount is now free to remove.

Old mount removed.

Compared old and new mounts and I was surprised to see that the old mount was actually in pretty good shape considering the car’s age. Maybe it was replaced by previous owners; hard to believe this one is still going strong after 180K miles and 17 years.

Old mount was in pretty good condition. Often the rubber tears out and the metal triangle collapses down, a sure sign of failure.

Old mount, top view.

Old mount, bottom view.

I could see some signs of the rubber tearing on the bottom which means it would eventually fail. Since I had the new part I decided to be proactive and replace it anyway.

Now we slip the new mount in place (it has a keying feature to prevent installing backwards) and bolt to the sub-frame.

New mount bolted to sub-frame.

Then lower the engine back onto the new mount and then bolt the mount to the engine.

New mount bolted to engine.

As expected the old mount was not seriously degraded so the new mount provided only a slight height increase.

New mount provides only a slight increase in gap since old mount was not badly worn.

Next we put the wheel back on, lower the car and tighten the wheel lug bolts and then run the engine to test for noise or vibration. No problems.

The white 850 sedan that I had been driving for 11 years has been sold to my oldest daughter so now the two girls both drive 850s. I’m rocking a nice 2013 Honda Accord now. I’m still caring for both 850s so they will still be featured in this blog.

The white sedan really let us down recently. Daughter reported it making strange noises and vibrations so I drove it to see if anything obvious was wrong. Sure enough, it made some horrible sounds accompanied by strong vibration and shuddering. Then the car stopped moving altogether even though the engine was running fine. No matter what gear I selected (this one has a manual transmission) the transaxle would not engage with the engine. We managed to push it off the road and called for a tow truck to come haul it to the repair shop.

Car had to be towed (or more accurately, dragged onto a flat bed truck and driven) to an independent shop.

I just didn’t have the time or equipment to deal with this problem myself so we had it towed to an independent shop specializing in European cars. I suspected the clutch was bad and that’s what the shop thought at first also. But once they started disassembling the transaxle to get to the clutch they discovered that one of the driveshaft bearings was seized up or something like that. Bottom line, one of the drive axles was broken and this caused the transaxle to not engage (something about differential gearing in there). The clutch still had some life left in it, they reported. So instead of a $1600 clutch job it turned out to be a $300 drive axle replacement. The clutch will need to be replaced at some point in the future but we bought some more time with this one. It’s back and running fine, although the shop found several things that needed attention.

The project car has been off to college since August so I haven’t posted anything lately. It came back for a fall break visit with my daughter complaining about the driver side windshield wiper. The arm was replaced early on with a generic part which was a mistake. Even factory arms have a reputation for bending out of shape and then not making complete contact with the windshield and generic parts fail faster.

Much of the left side was not wiped.

Hard to tell from these photos but the blade doesn’t make good contact on the left side of the windshield and this is a problem for the driver when needed. You can see how much I had to bend the arm to make even moderate contact and this is as much as I could improve it.

Even with arm bent a ridiculous amount the wiper blade wasn’t working well.

I even tried the suggested tricks to shave off some metal down at the base to allow the spring to pull the arm in tighter but that accomplished very little. The real problem here is the cheap substitute arm that I used the first time; it is weaker than the factory parts marked Bosch.

Because this is an important safety issue and because I already wasted money on a cheaper part, I bought an expensive factory part from the local Volvo dealer. Replaced it and now it wipes tight against the windshield like it should.

The Volvo 850 has a number of gas-charged shocks on it. Primarily the rear suspension shock absorbers and gas shocks as part of the strut assemblies on the front suspension. Suspension shocks allow linear movement with some resistance where they dampen natural oscillations.

I wanted to share this outstanding video explaining how gas shocks operate and how they fail over time. Particularly interesting is the multi-stage valves inside that respond to the force of different events:

I’m not trying to push a product, just acknowledging that the industry guidance for changing shocks and struts at 50K-60K mile intervals has some validity. By the time shocks or struts are visibly or obviously bad the shock is way past needing replacement and you would have experienced a big improvement in ride comfort, tire wear and handling if they were changed sooner.

Manual (non-electric) front seats and the wagon tailgate also have gas shocks, or, more appropriately, gas springs for lift support and I changed these in previous posts. They are less prone to constant vibration so they don’t have the same failure mode but the general principle of a gas-filled cylinder still applies. Over time and use the gas (usually nitrogen [N2]) will leak out and they lose their force to push the rod out and do the job. At this point they need to be replaced.

Struts were replaced, giving a huge improvement in ride, noise and turning smoothness.

Besides making squeaking noises and a less-than-comfortable ride, the struts needed replacement because the spring seat on the right side was failing. The rubber seat where the top of the strut spring sits is a well-known failure item on Volvo 850s. If you take a wrench to the upper nut and turn it, there should be little movement on a good seat and it should quickly snap back to the relaxed position. You can get quite a bit of twisting movement on spring seats that are failing and the nut spins freely when they are torn completely. The nut could twist quite a bit on this car so needed a seat replacement along with the gas shocks and who knows what else in these strut assemblies.

If you can get any real movement out of these nuts at top of strut, the rubber spring seat is failing.

Struts should always be replaced in pairs to give equal ride on both sides, even if only one is bad. In this case the right side strut had a torn spring seat while the left side was rather squeaky. Both really did need replacement.

Started by lifting the front of the car securely on jackstands with the wheels removed.

Strut replacement begins with car on stands and wheels off.

Next is to support the wheel hub with a jack to just take a little load off the strut.

Support the wheel hub so the shock is not extended.

To free the strut for removal involves unscrewing six fasteners in three locations. First unbolt the sway bar link from the strut mount (one nut).

Sway bar link disconnected from strut.

Then unbolt the lower strut from the steering knuckle of the wheel hub (two bolts/nuts).

Top of strut (bearing plate) unbolted from under hood allows the strut to drop.

There is also an anti-lock brake (ABS) sensor cable grommet that needs to be pulled out of the bracket on the strut.

ABS sensor cable pulled out from bracket.

The actual sequence here is not important but all four things need to happen to free the strut from the car. Now that it’s free, the support can be removed and the strut can simply be dropped down and removed from under the wheel well. The old struts (not original, but not sure when they were last replaced) were very grimy, worn and torn up.

Struts in bad shape.

At this point the strut is typically disassembled with special tools and then reassembled with new parts as needed. The spring is almost always salvaged and the other parts may be replaced depending on condition. It’s generally a good idea to replace everything but the spring.

For this job, however, and this is where many Volvo purists will get upset, I did not rebuild the struts. Instead I bought complete strut assemblies ready to go. This gives us new gas shocks, coil springs, dust boot, bumper, bump stop, spring seat, bearing plate, retaining nut, upper cushion and top nut. The quality of each of these may not be factory level but I’ll be happy if we get five years out of these. I used Gabriel ReadyMount complete strut assemblies (G57040). Three factors in choosing these: 1) Price was unbeatable with the pair running only $250 after instant rebate; 2) Time saved not rebuilding the struts; this cuts my effort down by at least three hours per car; 3) Favorable reports about these struts by certified buyers on their 850s. Volvo forums lean towards factory only parts, or at least high quality after-market level. I have no way of knowing where these complete assemblies fit in to this mix so this is something of an experiment. I will update this post if and when there is an issue with the struts.

Comparing the old and new strut assemblies is very favorable. The only missing detail is the ABS sensor wire bracket which needs to be screwed onto the appropriate side.

Complete strut assembly matches original perfectly.

Installation of the new strut assembly is straight-forward; just reverse the removal procedure. Orientation of the strut is impossible to confuse as both top and bottom have to be turned a certain way to install. The upper mounting is easy but the lower connection to the steering knuckle takes some effort to line up the bolt holes. As long as you can move the wheel hub around it can be done.

Secure upper part of strut loosely with nuts.

Strut roughly fastened at top.

Strut roughly fastened at bottom.

One extra detail is to screw the ABS sensor cable bracket into the appropriate side. The strut has holes pre-drilled for this and self-tapping screws are provided.

Screwing in ABS sensor cable bracket is easy.

Now it’s just tighten all the fasteners to the factory torque spec. Again, in no special order:

Lower strut secured to steering knuckle.

New fasteners are recommended for the lower strut bolts but I didn’t order any so just re-used the old ones.

Once everything is replaced and secure on both sides, just put the wheels back on and lower the car and make a test drive. Listen for any unusual sounds and feel how the front of the car rides and steers. For this task the ride was much improved; all the squeaking and popping was eliminated and the turning was smoother. I attribute much of the improved feel to the new springs which give more support than the originals with 17 years of compression on them.

New struts require front end alignment check and adjustment as needed because they alter the geometry of the front wheels, thus affecting caster, camber and toe. Fortunately we purchased lifetime alignment at Firestone so I’ll bring the car in for free alignment shortly.

I dissected one of the struts to see how bad it was and present a short photo essay below.

You need some kind of convenient and sturdy work platform.

Top nut and cushion washer can be removed at any time; these are not under spring compression.

To disassemble the strut further, you must compress the spring to relieve axial force. These two-piece compressors are most common but the cheap ones are scary fragile.

Alternative spring compressor is this massive monster that is sturdy but awkward.

I like the sturdiness of the big red one but it doesn’t clamp the coils as neatly as the two-piece compressor which is less likely to damage the finish (and let the coil rust). So the two-piece ones are probably better for these smaller coils (compared to larger vehicle springs). Just keep a close eye on them in case they show any signs of breaking.

With spring compressed the retaining nut can be removed. This takes a special star-shaped tool and another tool to hold the gas cylinder shaft from spinning.

Retainer nut removed.

Bearing plate pulled out from rubber spring seat nipple. They may have to be pried apart.

Spring seat, the weakest link in the whole strut assembly. Many folks recommend using a more sturdy part from the XC90 which fits the 850.

You can see the rubber torn in a ring around the shaft sleeve on top…

…and bottom.

Bump stop almost disintegrated.

Shaft protective boot badly torn which lets dirt get into gas cylinder seal and make it slide roughly.

With gas shock removed all that’s left is a compressed spring.

At this point if you were rebuilding the strut you would put in a new gas shock and replace any other worn parts as it is re-assembled in reverse order. There is a starting compression length for the spring that pre-loads the force when you tighten the retaining star nut.

Spring compression length spec when reassembling strut.

It’s also important to observe correct placement of the spring ends at top and bottom on the gas shock and spring seat, respectively.

$250 for two Gabriel ReadyMount complete strut assemblies on Amazon

Technical Notes: Strut assemblies are the primary front end suspension components. The coil spring around the gas cylinder provides the actual suspension of the chassis to the ground while the gas shock absorber provides dampening of the up/down motion for comfort and control. Unlike the rear suspension which has separate shocks and coil springs, these are integrated for minimal use of space. They need to rotate with the wheels when turning so there is a bearing at the top which allows for the struts to pivot with the wheels.

Finally solved that nuisance issue with the car vibrating/rumbling heavily when the car is in drive with the brakes on. Replacing the rear engine pad was the trick. Until now whenever the car was in neutral/park or reverse, there was minimal vibration felt in the driver’s seat. However, when in drive with the brakes applied, the car would really rumble and vibrate strongly. This problem is unique to the automatic transaxle where the idle torque of the engine is dissipated by the brakes. When the brakes were released, the rumbling would stop.

I zeroed in on the rear engine pad by observing the engine rotation when I had the upper torque mount bolt removed to allow it to move freely. In neutral or park the engine is centered on the upper torque bolt.

Upper torque bolt centered when…

…the transmission is in neutral/park.

In reverse the engine wants to twist towards the front of the car, applying pressure on the front engine mount/pad.

Engine twists to front when in reverse.

In drive the engine wants to twist to the rear, applying pressure on the rear engine mount/pad.

Engine twists to rear when in drive.

Observing this it is apparent that the rumbling in drive only must be related to the rear engine mount so I replaced the rear engine pad (left side of transverse-mounted engine). This made a huge difference and I was not surprised at the results when I saw the old pad and installed the new one.

Started replacement by unbolting two items from above before the car was lifted. First is the upper torque mount. Unbolting this allows the engine to move up on the left side of the car, just above the rear engine pad.

Upper torque mount unbolted.

Next is the upper nut fixing the rear pad to the engine. It’s deep under the hood so a long socket wrench wobble extension really helps, as does removing the air pre-heat flex pipe for more direct access. It can be done with a shorter socket working underneath all that but you need long arms and some dexterity.

Upper rear engine pad nut removed.

For this it helps to have a long socket wrench extension and to remove the air pre-heat pipe.

Now the front of the car needs to be lifted securely onto jackstands.

Front of car lifted onto jackstands with rear wheels blocked.

Three things need to be unbolted with the front lifted. First the lower torque mount to the automatic transaxle. This allows the left side of the engine to lift up.

Lower torque mount unbolted from sub-frame so engine can move up.

Second the bolt securing the rear engine pad to the frame. This is recessed so you need a socket wrench extension run between the frame and drive axle.

Rear engine pad unbolted from below.

Long socket wrench with wobble extension needed to unbolt engine pad from below between sub-frame and drive axle.

Finally unbolt the engine from its left mount to allow freedom of movement at the rear of the engine. This is not in the factory instructions or in the Haynes manual but I found it to be necessary to get enough movement of the engine. Others on the internet also mention this requirement. For this the right front wheel needs to be removed and the plastic flap lifted up for access.

Right side engine mount unbolted (two screws just below and left of main pulley).

Now that everything is freed up we need just lift the left rear corner of the engine to remove the old pad and install the new one.

Old (probably original) pad unbolted top and bottom, ready to pull out.

Service manuals indicate 30mm maximum lift to avoid damaging the inner tie rod ends so I took a reference measurement of the bottom of the engine (actually, transmission body bolted to the engine) to a point on the sub-frame. I measured about 10mm.

Engine lifting reference measurement about 10mm.

For lifting I used a floor jack with a block of wood to spread the load and cushion it. I got just under 30mm of lift before it started lifting the car, indicating that I had maxed out engine movement.

Lifted left rear corner of engine nearest pad.

The rear pad was now free to move so I pulled it out for inspection.

With engine lifted pad was now free.

Empty space where pad was located.

The pad fell into three pieces when I removed it. The lower metal mount had separated from the rubber cushion and the safety wire came off. Comparing old and new mounts, the original was significantly shorter and somewhat softer than the new one.

Side-by-side comparison of old and new pads.

You can see how much length was lost in the old pad in the tapered section.

I used an after-market pad for about half the price of a factory part. I’m not concerned about getting another 10 years life out of this car and I’m trying to be economical.

When installing the new pad, there is an orientation to be observed. The triangular pin needs to fit into the offset hole near the upper bolt hole.

Triangular pin must locate in this…

…mating hole offset the axis to provide pad orientation.

It took a little bit of fussing and twisting to get the new pad installed but did not require forceful prying. Guess I had just enough lift to slip the new pad in.

New pad in position, ready to lower engine.

The engine was lowered and as expected, the resting height was now greater with the new pad. The old pad had collapsed by the 9mm measured difference.

Engine lowered and resting on new pad.

About 19mm clearance now with new pad. Old pad had collapsed 9mm over time.

Now all we have to do is fasten everything back together again and torque to specification. Right engine mount bolts, rear pad lower bolt, lower torque mount nuts and then wheel back on right front.

Right engine mount bolts secured.

Lower rear pad bolt secured.

Lower torque mount nuts secured.

Lower the car off the jackstands and then secure the rear pad upper nut, pre-heat pipe and upper torque mount.

Upper rear pad nut secured.

Upper torque mount bolts secured.

At this point I was not surprised but was very pleased to confirm that the strong rumble and vibration was gone when the car was in drive and the brakes were applied. This one has been bugging me since we got the car a year and half ago but has never been my highest priority.

I suspect that the rear engine pads in automatic transaxle cars driven mostly around town get a lot more wear and will fail sooner than manual transmission cars because there is so much more force and wear on that pad from all the idling in stop and go traffic.

Oh, well– that muffler patch didn’t hold. A couple of the larger holes blistered out their patches and there is at least one small hole again, so now we need to replace the muffler. As mentioned in post #101, exhaust leaks are a safety concern with the potential for deadly carbon monoxide gas building up in the cabin.

This is a long and detailed post. If you’re interested in the topic, read on. Otherwise, here is the…

Summary: Previous attempt to patch muffler holes failed. Removed old muffler assembly (large muffler, long inlet and outlet pipes). Installed replacement assembly. Original exhaust tip/tail pipe was coming apart so I rigged it up temporarily while waiting for a new end pipe.

Details: In researching a muffler replacement I learned a few interesting things. First, it is unusual for Volvo mufflers to fail, unlike most other cars. The factory mufflers are made of steel and coated with aluminum (aluminized steel) for corrosion resistance. I read on the internet that Volvo has a lifetime warranty on their mufflers, but after checking with the dealer service shop this does not apply to North America, if it does anywhere, so that may be an internet legend. One local independent Volvo shop doesn’t stock mufflers because he never sees them fail and would have to special order the part. We surmise that this car was exposed to salty ocean air somewhere in its life because it came from coastal California originally and when we bought it there was a Texas beach parking sticker on the windshield. I suppose in colder climates where the roads are salted for ice they see more exhaust failures, or, more likely, the cars rust out faster and are scrapped at a younger age.

Second, this car has a large and unusually-shaped muffler and none of the exhaust repair places have a generic replacement, so we’re stuck buying a factory muffler or an exact-fit after-market unit.

Third, the muffler comes with long pipes permanently welded at inlet and outlet, so it’s more than just a muffler; there are also several feet of exhaust tubing. The whole assembly is about seven feet (2.1m) long.

The good news is that there is only one simple clamped connection aft of the catalytic converter directly below the hand brake lever. The rest of the muffler/pipe assembly just hangs under the car. So replacement is fairly straight-forward but it’s not physically easy.

For a replacement I hesitated at the price tag of a factory muffler assembly. The best price I could find on the only valid part number that a Volvo dealer shop gave me (31372150) is about $400. Add an hour of labor if I paid someone to do the work, plus any other parts that may need to be replaced.

So I decided to do the work myself and buy a quality after-market muffler assembly. I chose a direct-fit Bosal unit, part number 290-517 for under $200. The unit fits exactly and the quality and workmanship are close to Volvo OEM. At any rate, even if it doesn’t hold up as long as the original one, I doubt that this car will be around another 17 years.

The biggest surprise with the new muffler is that the supplier just slapped shipping labels on it and sent it via FedEx. Showed up on our porch with no box or packaging.

New muffler assembly arrived with no packaging; just as shown here.

At least they wrapped some protection around the pipe ends and it is in good shape. I guess these mufflers are pretty robust and don’t need much packaging. The supplier claims this is standard procedure.

To start the replacement, I removed the end pipe from the exhaust tube while it was still on the car to reduce the weight by a couple of pounds. With the exhaust still on the car another advantage is that the tube is fairly stable for wrestling the rusted end pipe off.

End pipe before removal.

End pipe before removal. Fixing bolt removed.

The end pipe was also pretty well stuck on the exhaust tube so I had to break it loose with a hammer and wood block, then rock and twist it off.

End pipe removed.

End pipe removed.

Unfortunately the fixing screw was corroded solid so the nut just pulled out of the end pipe.

End pipe fixing bolt was fused to press nut so it pulled through the corroded pipe when I tried to unscrew it.

End pipe before removing corroded bolt. It’s pretty corroded just at the seam.

To replace the muffler assembly I lifted the the car and set on jack stands as high as practical to get plenty of working room under there.

Lifted the car and rested on jack stands.

Then I unbolted the exhaust coupling beneath the driver’s seat. This took some effort as the bolts were rusty with years of heat working. I gave them a good shot of penetrating oil (PB Blaster) days in advance and another dose before trying to unbolt the clamp.

Sprayed penetrating solvent onto clamp bolts days in advance to help loosen them up.

I did this first because it was the big unknown that might cause lots of trouble or even make me resort to taking the car to a shop. Fortunately a socket wrench with long arm did break the bolts free so I was pleasantly surprised that it went easy and well. The clamp and fasteners were in much better shape than they appeared.

Once the bolts are loose, the nut on top will spin free. Need a short socket to hold the nut.

Clamp removed. Joint still stuck together rather solid.

Now that the exhaust pipe was unclamped I unhooked each of the exhaust hangers, starting with the muffler.

Released muffler hangers both sides.

Moving to the back with the two hangers near the end of the tail pipe. Note the muffler and tailpipe hangers are slightly different parts.

A shot of silicone lube really helps the hangers slide off the chassis hooks.

Tailpipe hangers released.

With all four hangers loose the whole exhaust is free and rests on the rear suspension arm.

Now we need to break the corrosion weld in the front joint so the whole assembly is loose. For this the easiest thing was to grab hold of the muffler and twist along the axis. The unclamped joint to the catalytic converter broke free easily this way and the whole assembly could now be removed.

Coupling freed up by twisting muffler.

Before pulling the muffler out I removed the rubber hangers so they wouldn’t get damaged or snag on the chassis.

Rubber hangers removed.

The whole muffler assembly weighs about 30 pounds (13.6kg) so it’s not too heavy to handle under there. Having a helper is best but I was able to muscle the thing around. Because of the way it fits under the car, the muffler assembly must be pushed towards the front of the car to remove it to clear the rear suspension arms.

Now comes the trickiest part of the whole process. The tail pipe has to snake over the rear suspension arms and through a small area between the fuel tank and the rear spring. The tail hanger hooks really stick out so the whole assembly has to twist around at different angles while drawing the muffler forward. For this to happen you need a fair bit of clearance between the muffler and the ground. I was right at the edge for height with my jackstands. The muffler hooks really scraped the driveway but I managed to pull it out.

Before clamping the joint we need to position the muffler in its approximate location so things are stable and in place. Used the car lifting jack to support the muffler.

Supported muffler with jack to keep joint in place.

Also cleaned up the original clamp parts with solvent and a wire brush.

Cleaned up original clamps and fasteners.

Secured clamp over joint and tightened it. I pulled hard towards the back to make sure it didn’t separate.

Clamped joint with original parts.

Now it’s time to start hanging the muffler and tail pipe. Slipped the rubber hangers over each hook on the exhaust. It is easier to hang with the rubber hangers attached to the exhaust than it is to slip the exhaust into the hangers already in place. One of the rubber hangers was really cracked and coming apart so I replaced it with a new part. Then lifted the muffler and/or pipe and positioned the hanger on each chassis hook one -by-one.

Replaced one bad hanger with a new part.

Once again, silicone lube really helps the hooks slide into place.

There, we’re done with the muffler assembly. I ran the engine to check for leaks while the car was still on stands. No apparent leaks and it sounds just like a typical 850 exhaust note– good news! Took a couple of hours so far

But we’re not quite done and the rest took most of the afternoon. The exhaust tip or tail pipe is called the end pipe by Volvo. This is the last 11 inches of pipe that connect to the end of the muffler outlet pipe and through the cutout in the bumper. I removed the original one way back at the beginning and as mentioned it was broken. Turns out things were even worst because a big part of it–a internal tubing sleeve–was fused to the old exhaust pipe. So we need a replacement.

End pipe not only lost its fixing screw but the inner sleeve was stuck to the old exhaust tube.

Unfortunately it’s not a stock part at the Volvo dealers and they want $55 for one with one week leadtime. After-market tailpipes run about $40 but none are stocked anywhere in town. So I ordered an aftermarket part to be delivered next week and rigged up the old one to be temporarily functional. Ugly but secure. Just not good long-term.

Played around with various techniques and a visit to two hardware stores before I finally found something that worked, more or less. Basically added a pair of new fixing bolts to clamp the tail pipe to the exhaust tube.

Drilled a couple of holes near the original fixing bolt hole.

Ran a pair of bolts through the holes held captive by two nuts inside.

Shoved the end pipe over the exhaust as far as the nuts would let it go, then tightened the bolts against the tube to secure. Nuts want to spin so a screwdriver was used as a wedge.

Temporary end pipe looks OK and is functional.

Shoved a mass of steel wool into gap between end pipe and exhaust tube to minimize gases forward.

There, it’s all in and ready to roll. Sounds good now and no more concern about exhaust leaks. Test drive OK except it reminded me that I should have removed all the labeling from the muffler and tubing. I had removed what I could but some labels were really stuck on so I just gave up. Unfortunately they got very smelly with some smoke after the exhaust heated up. So next time (if there is one) I will go to the effort of removing all labels.

Couldn’t get these labels off easily so they started removing themselves in a smoky, smelly manner after the pipe heated up.

Used a Walker 41827 end pipe, which was much cheaper than the factory part and it fits just fine. Note that the wagon part is slightly longer than the sedan pipe, which is a different part number (both Volvo and Walker).

Started by removing the label (see, I learn from my mistakes!) with xylene solvent and a putty knife, then wiping off with towels and finished with all-purpose cleaner and towel dry.

Used solvent to soften label, then scraped label off and wiped remaining residue off.

Comparing factory pipe (R) to new Walker pipe (L), you can see the after-market pipe is tapered to fit the exhaust where the factory part had a sleeve inserted in the end beneath the fixing bolt.

New pipe necks down to fit over exhaust tube where factory pipe had an internal sleeve.

Slid the new pipe over the end of the exhaust just past where it necks down and tightened the fixing bolt. I chose to rotate the pipe where the bolt was parallel to the ground.

Bolt turned parallel to ground.

Tightened fixing bolt on exhaust pipe before it necks down.

Positioned just right.

Looks great now with the new end pipe.

$197 for a mail-order muffler with free shipping and no sales tax (and no packaging!) +$40.90 for end pipe = $238 total.

Half of the lights on the Volvo factory radio have been out since we bought the car. It was hard to see the radio buttons and controls in the dark without them.

Two lamps out so driver can’t see buttons on the right side after dark.

I think this is a safety issue since at night the driver’s eyes spend more time trying to see and figure out all the invisible radio buttons and less time on the road. So I should have made this a higher priority.

Anyway, this is a relatively simple fix and rather low cost. There are two good on-line turorials for this and I recommend them both:

Neither applied 100% to my experience but they both cover the basics. Mainly because these writeups cover the CD version SC-815/6 and this car had the cassette tape feature, SC-710.

Getting the factory radio out of the car is really simple. Just push in the two rectangular tabs which will then pop out to create finger pulls. The radio is pulled out using these handles.

Push in tabs to release radio with finger pulls.

Radio pulled out most of the way.

Before unplugging power make sure you have the radio security code written down somewhere so you can use it again. Unplug the radio cable by pulling straight back and push the release button to unlatch the rectangular connectors before pulling them out.

Radio uplugged.

Take the radio to a bench or table with appropriate padding to disassemble.

Radio ready for disassembly.

First you pull the volume knob and tone slider knobs off and set aside (no tools needed).

Volume control knob and three slider knobs pulled off.

Next you have to get the front bezel off. A couple of screws need to be removed on each side (maybe more with SC-81X).

Two screws on both sides need to be removed.

Now you need to simultaneously release six plastic tabs while pulling the bezel forward. This isn’t easy so it helps to release the four on top and bottom and wedge something under the tab (such as a toothpick) to keep them released. Then release the two on the sides and you can pull the bezel off.

Pry up on four top/bottom tabs…

…and wedge something under each one to keep it unlocked.

Pry up on both side tabs to release bezel.

With the bezel off you can see the printed circuit board (PCB) which contains the pushbuttons and lights.

With front panel (bezel) off you can see the PCB underneath.

Light pipes on back of faceplate/bezel direct lamp light to individual buttons.

Now you need to remove the PCB to get underneath it to remove/replace lamps.

Remove three screws to release PCB.

With this cassette model there are three screws holding it in place. With the CD version there are twist tabs that secure the board.

Now just lift the board up/out by gently prying and wiggling. The lamps are screwed into the PCB from behind.

Back side of PCB showing lamp sockets (black).

Since we’re going to this much trouble, we will replace all the lamps, even those which are still working. They are likely to fail soon anyway. This way they are all the same age and brightness.

This cassette version has six lamps while the CD version seems to have only five.

1/8 turn CCW loosens lamp from PCB so it can be pulled out from behind.

All six lamps removed from board. You can see the holes where they were installed.

The lamps have a blue filter sock over them to diffuse the light and give it a cool color. Need to remove these blue booties and transfer them to the new lamps.

Carefully twisted and pulled the blue boots off the old lamps.

Replacement lamps from Honda (part number 35505-S84-N01. Gray plastic base is different but color is not important.

On my 850 sedan I used JKL part number CNW1-23 which works fairly well. You can also get the blue boots, JKL 39-02-5A. Both of these can be purchased from Mouser electronics.

Honda replacement lamps work perfectly.

Blue gel filters transferred to new lamps.

Now screw the new lamps into the board.

New lamps installed onto PCB.

New lamps with filter socks installed.

Now plug the board back into the unit and secure with screws again.

The CD version seems to also have a lamp or two behind the LCD display for backlighting. This version has two lamps buried deeper inside. Those use different lamps that are soldered to the board, which would require some more electronics skills and different lamps. I didn’t deal with that here and will wait for them to fail before replacing them.

LCD backlight uses two different lamps soldered to another PCB. These were not replaced here.

Now just put the whole thing back together and plug it into the car for a test. Have to do this after dark to see if all the lamps are lit.

Not trying to solve a problem here, just a little preventive maintenance (PM) to delay power steering failure.

As far as I know this car has mostly original power steering fluid in it. Now 17 years old with 175K + miles on it, the power steering fluid was old and smelly so I decided to flush it and fill with fresh fluid. Like many cars the Volvo 850 has no specified maintenance interval for power steering fluid so it usually gets overlooked. I guess the manufacturers think the pump will be replaced eventually so you’ll get new fluid. Problem with this idea is that the fluid does degrade with time and temperature and who knows what else. Plus tiny metal particles that wear off in the pump and steering gear and swim around in there that could cut into seals. So it’s just a good idea to flush the hydraulic system out and put fresh fluid in there every so often.

First thing to do is lift the front end of the car so we can rotate the wheels easily without scuffing up the tires and driveway.

Front end on stands allows easy movement of wheels to flush the steering gear and hoses.

Next is to lay down some oil absorbent pads because this will be messy.

Even when you work quickly and carefully some power steering fluid will be lost and drip onto the ground.

Started by dipping a strong magnet into the power steering reservoir and then rotating the wheel from stop to stop with the engine running. Thought I would catch any metal particles that were stuck in there with this but was pleasantly surprised to see very few. That means that the pump and steering gear aren’t wearing badly.

Dipped a strong magnet into the reservoir to capture any metal particles…

…but there were only a few tiny ones (good news!)

Next I used a bulb syringe to suck out as much fluid as possible from the reservoir. This minimizes the mess in the following step.

Sucked fluid out of reservoir.

Then I unclamped the power steering return hose at the reservoir and pulled the hose off. This is where it gets messy as whatever fluid remains in the reservoir will leak down onto the alternator. As quickly as possible I slipped a vinyl cap over the nipple to stop the flow.

Blue vinyl cap seals return port to keep fluid in reservoir.

Fuzzy close-up view of capped return port. Hose just removed is to the right.

Next I slipped a length of 5/8″ clear vinyl tube over the hose just removed. It’s just the right size to seal but still slip over the hose easily. The other end of the hose went into my waste container.

5/8″ clear hose slipped over return hose fits nicely.

Other end of clear hose drains into waste container.

Filled the reservoir with fresh fluid. Volvo spec for this is Dexron II or III or Mercon automatic transmission fluid (ATF).

850 power steering fluid is specified to be Dexron-III or Mercon auto trans fluid (ATF).

It’s best at this point to have a helper to start/stop the engine and run the steering wheel back and forth. The basic procedure is to run the engine and quickly spin the wheel from left stop to right hard stop and repeat. Fluid will quickly drain from the reservoir through the steering gear then back up and out to the waste container via the hose. So you need to keep filling the reservoir while it’s draining. If you’re working alone you have to work quickly and stop the engine before it runs dry, then refill frequently.

Flush with fresh fluid while draining into waste container.

I ran about two quarts of fluid through to flush. The old fluid was rather smelly, not quite burnt, and fairly dark. Needed to be changed. New fluid has a mild odor and is a transparent red color.

Old fluid was dark and smelly. Half of what you see here is fresh fluid from the flushing process.

Then you re-connect the return hose to the reservoir and re-fill the reservoir.

Re-clamp return hose in position on the pump reservoir.

Run the engine again while spinning the wheels back and forth until all air is bled out of the lines (no more foam).

At this point we’re done flushing and we just need to make sure the fluid level is correct.

Lower the car back down to a level surface and re-check fluid level. Add or remove fluid as needed. It’s probably a good idea to check the level again in a week or so in case there was still some air in the system.

Noticed a different sound from the car when standing next to it while idling. Sort of a sharp gurgling sound that seemed to come from under the left rear passenger seat.

Crawled under there with the engine running and could feel exhaust pressure coming from several holes in the muffler. Oh boy, time to repair or replace.

Multiple holes in bottom of muffler of varying sizes.

Exhaust leaks are potentially dangerous if deadly carbon monoxide (CO) creeps into the cabin. If the floor is solid and tight, not much exhaust can get in but cabins aren’t always exhaust-tight. For this reason automotive inspections don’t allow exhaust leaks ahead of the tailpipe. Better play it safe with this and fix the leak, even if we have several months left on the state inspection tag. The proper way to repair this is to replace the muffler but right now we don’t have the time or money to do this. So I’ll patch it temporarily to fill the leak and make it safe until we can have the muffler replaced. Basically buy us some time to do it right. I’m also curious to see how long this method holds up before it fails or more holes break open.

If they are not obvious, one good way to check for exhaust leaks is to block the tailpipe with a rag or something. The engine should stall if the exhaust is tight. If you block the tailpipe and the engine stays running you can locate leaks by listening for noise and feeling for hot gases.

I searched the internet for a variety of exhaust repair products. Few had good reviews. Found a couple of Permatex products at my local auto parts store that looked promising. Both might work OK on their own and the package suggests that a combination of the two makes a secure, permanent repair. I’ve learned not to trust marketing hype so am not overly optimistic. If it lasts six months I’ll be content.

Tried using these two exhaust repair products from Permatex.

All exhaust repair starts with scrubbing loose rust and dirt off the metal first so I had to do some prep work. The first layer of patching is a high-temperature (1000°F) paste or putty that is spread over the holes, then fired to cure it hard and strong. The second product is a tape or bandage that is also cured with heat.

Applied one coat of paste. Putty knife didn’t work well on this convoluted surface so used a gloved finger, pressing into the holes to seal.

Instead of running the muffler hot, I cured the putty with a heat gun. Too much heat makes it soft and bubbly so went slow and easy.

The hardened light gray putty is hard and secure so is a promising fix. Time will tell.

The tape/bandage would not stay secure hanging below the muffler at all. The adhesive simply wasn’t strong enough so this was a disappointing experiment.

Bandage just wouldn’t stick to muffler so I gave up on this second product.

Instead I slathered another coat of the putty over the first pass, hoping this helps even more.

2nd coat of paste is kind of thick and lumpy but hopefully makes the patch hold up well over time.

Looks good and tight now and sounds much better. No sound from below rear seat and I could feel no exhaust pressure under the muffler as before. I’ll keep an eye on it to see how well it holds up; will report if the putty fails.

Update 7/14/14: The patch failed pretty quickly. It seems that those four large holes had too much surface area to cover and the putty blistered out in a couple of spots from hot gas pressure and a couple of cracks formed so I can now feel exhaust pressure hissing through the new holes.

Cracked blisters allow exhaust to escape.

New muffler will be delivered shortly and I will replace it. Check out those details on post #104.

Wow! One hundred repair and maintenance tasks since we first got this car back in February 2012, along with 37 additional blog entries. I would really like to post something exciting or significant for this century mark but the timing is just not right so #100 is relatively trivial.

As mentioned back in task #90 when adding a remote lock/unlock feature to this car, I planned to also add an alarm horn and dashboard indicator. This makes the keyless entry/alarm system complete.

Picked up both the dash top indicator and alarm horn from wrecked cars in a salvage yard. Removing and installing these was not as easy as I had hoped but worth the effort.

The red light (LED) on top of the dashboard just below the forward center of the windshield come in two flavors. One is for cars with electronic climate control (ECC) and this one has an additional light sensor on the unit. My first mistake was pulling one of these from a scrap car only to discover that the wiring connectors are different.

Module for alarm indicator (white bubble) also includes light sensor for ECC equipped cars. Not the right module for this car with manual climate control.

So the next time I visited a salvage yard I made sure to get the light unit with a single red light.

Lacking a factory alarm system the hole filler was in place on this car and that was removed by prying it out. This was easy to do because the forward part of the dash just below the windshield was badly cracked, especially around this rectangular hole.

Removed filler piece to leave square hole for LED module. Wiring is underneath.

The cars come pre-wired with most options and accessories so there was a functional wiring connector below the hole. Fishing this connector out of the hole was much more difficult. There is so little space just above the hole that I could not grab the wires to pull them out. Neither is there any real room for manipulating normal tools down the hole. Having very small hands or specialized tools would be needed. Or removing the windshield, which would be a last resort. Since I had to pull the entire dash out to repair the forward mounts being broken, I had direct access under there so pulled the wire through the hole and taped it on top. It was already above the hole when I reinstalled the dash.

Then I simply plugged the new LED module in and verified that it blinked when the doors were locked. I had to glue it in place with black silicone because the dash was so badly cracked and broken (probably because of broken front dash mounts) that there were no solid edges to hold the unit in place. Looks amateurish but you don’t really notice it unless you’re looking for problems.

Since square hole was really broken, the module would not snap into place. Had to glue it down with black silicone.

Blinking red light is most visible in low light and tells you that the car is locked and may be a deterrent to a thief.

The horn is also pre-wired whether or not the alarm is installed. Access requires removing the cowling behind the hood just in front of the windshield. Some effort but not too bad, about a half hour total. A single bolt holds the horn in place. I just removed the cowling and bolted the “new” alarm horn in place, then plugged it in and tested it before replacing the cowling and wipers.

Photo essay below is the basic procedure for installing the alarm horn.

Alert reader Ken Gill sent a message about a problem with the rear brake job in post #70. He experienced the same thing and observed that I had not driven home the caliper guide/retainer pins. They could not be hammered secure because the retainer ferrules were too large. I failed to realize this and mistakenly thought they were secure enough. Boy, was I wrong.

This safety task was to fix the problem with very loose and nearly inoperative rear brakes because of the loose pins. Scary because my girls were driving around for months with faulty rear brakes. I also updated the original post with a lengthy description of the situation and remedy. This is an important safety issue so please read my comments if you have any concern that your rear brake pins are secure.

All better now, thanks to Ken’s heads up.

Which reminds me to ask for reader comments when you see something on this blog that was done wrong or could be improved. We have hundreds of readers all over the world (on six continents!) who find it useful for DIY 850 drivers. I want it to be complete and correct, so don’t be shy.

One day we noticed that the lens was missing from the right front corner light (front parking/turn signal lamp) assembly.

My first thought was vandalism where somebody smashed it but after examination I observed that the lens that wraps around from font to side was completely gone with no trace of damage. It seems that the factory light assemblies have the lens secured with adhesive or tape. Now I’m guessing that the glue simply came loose after 17 years of heat, sunlight and vibration and that the lens simply fell off while driving down the road.

Lens missing

Fortunately the lamp housing was still attached to the car and functional so no worries or hurry here. Bonus that the Volvo part number is molded into the lamp housing and visible so I just wrote that down and went searching for replacements. Had a hard time identifying this part on my favorite factory parts locator, volvopartswebstore.com, or in Vadis so I really did need the part number.

This particular part is Volvo 6817774 and costs over $70 with shipping for a new factory part. That’s a little steep and I was hesitant to get a junkyard replacement because they are likely to be in poor condition. After looking I couldn’t find any at a scrapyard anyway. Back to the internet, I did find what appears to be a high quality aftermarket replacement with good customer reviews from Amazon. Ordered one only to have the supplier inform me the next day that there is a recall on that part so they wouldn’t ship. So I ordered another part on Amazon and it looks great. Apart from plastic color I can’t tell much difference between the factory original part and this one.

Good news for this task is that it doesn’t require any tools. Just open the hood and release the spring holding the assembly in place.

Removing old lamp assembly with missing lens.

After unplugging the wiring harness we can work on swapping a couple of parts.

Remove spring and lamp socket from old assembly.

Side-by-side comparison of the old and new light assemblies.

Install spring and socket onto new light assembly.

Now just put the new assembly in place by plugging the harness in and inserting the module in place and locking with the spring hook.

New light assembly installed. Looks beautiful. Original one on left side seems hazy and crusty in comparison.

Did a quick check of light function with running lights and turn signal. Working fine so we’re done with this one.

Functional checkout OK.

Now I’m keeping an eye on other light assembly lenses on both cars to see if they show any signs of coming apart, or if this was a rare event.

As mentioned in post #95, I scraped the top off the shift knob when wrestling the dash back into place. I was planning to replace it eventually because even before this damage the knob was in rather poor shape.

Note: this applies to the automatic transmission (transaxle) 850 variants so likely only the North American readers will be interested in this. But I would love to hear from people in other continents who have automatic transmissions to gauge how common it is outside North America.

Tore shift knob up when replacing dash.

Original knob was already in bad shape. Top had a heat-melted plastic look and feel with lots of cracks. You can still see what it looked like on the top right.

Pulled a couple of knobs in varying condition from a scrapyard at a very good price (see previous post on this if interested).

Two shifter knobs pulled from scrapyard cars.

One knob was a matching dark color and had an intact release button but it was fairly cracked. Still better than knob now in car.

The vinyl coating on the other knob was in excellent condition but it was a lighter color tending toward brown. It had a broken release button.

I prefer the knob in better condition despite the color so needed to swap the release button with the other knob. This isn’t terribly difficult but it does take some mechanical dexterity. And the otherwise excellent instructions found on IPD for a shifter knob repair kit gloss over a very important step of getting the upper pin into a slot in the plastic lever inside, which takes some manipulation.

The spring which apparently fails frequently (enough to create a repair kit) was in good condition so I just swapped the good button to the good knob.

Push button outwards by pulling with fingers after moving it out with a screwdriver from inside.

Release spring from button, then push pin out to release upper part of button, then unclip lower part to remove button.

Now I have a good button to transfer to the good knob. Repeated this button removal for the good knob to remove the broken button. Then I installed the good button onto the good knob:

Clipped good button onto bottom pin of good knob and then positioned spring properly onto button.

Pulled internal lever out to line up with upper pin, then secured pin in slot.

Then I just pushed the button all the way in and it was ready to go.

Now that I had a new knob assembly in good shape, it was time to replace the knob. It’s much easier to pull the knob when the shifter is in the neutral position. Obviously not when the engine is running, and you can do this by inserting the key and turning it one or two clicks clockwise without starting the engine. Then push the shiftlock override button in and move the shifter to the middle.

Move shifter to neutral position with engine off by turning key partially then pushing shiftlock override button while moving lever.

Removing the old shifter knob isn’t terribly hard; you just pull it straight up very hard. I get better leverage while kneeling on the passenger seat than when sitting in either of the front seats. It’s also more ergonomic and easier on my lower back.

Pull hard straight up to remove shift knob.

Then installed the new knob by simply pushing it down into place and then pulling the leather-like boot covering the shaft back up to the knob and snapped into place. The plastic tangs at bottom of the knob clip under a square plastic ring inside the sleeve.

Pulled shaft sleeve back up to knob and locked into place.

All done and the new knob looks better than it appears in the photos in real-life. There are several different shades of gray in this interior anyway.

For various reasons I needed quite a few parts to replace or add to the car and several of these are either unavailable or expensive. At times like these it’s good to have an automotive salvage yard (junk yard, scrapyard, wrecking yard– whatever you want to call it) nearby with several 850s. As mentioned in the post on where to get parts, the scrapyard is an excellent source of used parts, particularly for large and/or expensive pieces. The downside is that they may not have the part on a car (or the wrong color) and the condition is always as-is, so plastic and rubber parts will be dry and brittle. It’s also messy as you are climbing in or around wrecked cars and you need to bring the right tools to remove whatever part you want.

All that said, I think it’s worth the trouble and scored a boxful of parts, mostly from one 1997 850 that hadn’t been picked clean yet.

Miscellaneous parts pulled from a few different 850s and an S70 in a salvage yard.

The scrapyard is an hour drive each way and I spent almost two hours in the yard but it was worth the trouble. Cost was very low for all this: $42.

For those of you who haven’t experienced a junk yard pull, here are photos of cars typically found in a scrapyard. It’s a little creepy when there are personal effects left in the wrecked cars. The cars are frequently a real mess with loose parts strewn all over so it’s often a lot of work to pull a part that you need, if the parts are even still with the car.

Driver’s side sun visor was worn where it clips into the roof so that it was loose and vibrating and would easily pop out of place.

Vinyl worn off so that visor was loose.

The proper fix would be to replace the whole visor but that would be expensive as a new part or would likely be fairly worn as a used or salvage part.

Started a repair by carefully cutting away the remaining worn vinyl around the retaining rod where it clips to the roof.

Repair begins by cutting away worn/torn vinyl from rod.

First tried to increase the diameter of the rod to match the clip by slipping some plastic tubing over it. Even when I cut a diagonal line, this popped off the rod when unclipping from the roof.

I really couldn’t think of a good solution to slip on or clip on something that would increase the diameter of the rod. So I tried using epoxy putty to build up the diameter. It’s hard to get it nice and smooth and just the right diameter but I did as best I could.

Applied epoxy putty around rod to build up diameter.

I made the diameter of the epoxy so that it is snug in the clip. It cures quite hard and adheres well. The putty can be filed or sanded smooth but I don’t think I need any refinements.

Visor now snaps in tightly. A little ugly but works well enough.

This works quite well, at least for now. Snaps in and out well and rotates up and down. We’ll see how well it holds up long-term but it should be stronger than the original vinyl.

Well, this was a big project, taking up a large chunk of my Easter weekend.

I grew tired of listening to the dashboard rattle and squeak with minor road disturbances and my daughters who normally drive this car confirmed that this nuisance bothered them as well. At first I thought it was due to deteriorated cushions in the dash top cover or pad. So I removed the top pad and found no real cause of squeaking or rattling, such as a worn foam strip. This was also my last chance to do anything big before one daughter soon returns from her semester abroad, as the car would be un-driveable for a few days.

Dash pad/cover removed to look for looseness/squeaks.

Did a little research online and learned that the 850 has a very common problem with the front dashboard mounts failing, resulting in the whole front of the dash to be loose. That’s what causes all the rattling and squeaking. This was verified on this car when I found I could move the whole dash freely front to back with the pad off, meaning the front bolt mounts were completely broken free.

So I removed the dash entirely to find what I expected: the front mounting tabs (nut retainer plastic) had torn away completely from the dash assembly.

Front mount broken off, remained in place when dash was removed.

One mount completely ripped out of dash, leaving gaping hole.

All four mounts broke and stayed behind on chassis when dash was removed.

Fortunately the mounts were somewhat intact, not shattered into many small pieces as some people find. This meant a relatively easy repair, and I adapted fixes as suggested by several people in Volvo forums. Repair was easy but getting the dash out and re-installing is quite an ordeal.

First I used cyanoacrylate (Super Glue) to secure the broken plastic mounts back into place.

Super-glued mounts back into position as best as possible.

Then I applied epoxy putty to the broken joints for a stronger bond. These two steps are intended only to get and keep the nut in position temporarily; they are not expected to hold firm.

Putty epoxy used to further secure mounts in place.

Then I screwed a short length of metal pipe strap over the mounts to create the new fastener. The repaired mount now consists of the strap secured to the dash with the nut captured underneath. Located the large holes directly over the nut thread.

Metal pipe strap screwed into dash forms new mount.

Repair looks cheesy but it is solid and really works.

All four mounts created by strapping over nuts.

Verified mounting screw cleanly passes through metal strap in all four positions.

Re-installed the dash and was pleasantly surprised that all four repaired mounts held together and I was able to tighten them all down. I was going to be happy with only three solid ones and settle for two. Four is just totally sweet!

Update 4/24/14:While others have concerns about the exact positioning and contour of the strap, I found it was not critical. The strap was loosely wrapped around the mount shape in some cases. Also had no trouble getting the long bolts to line up with the captive nuts. For those who are curious, I used #8 truss head self-drilling screws, 1/2″ long, using care not to over-tighten them and strip the plastic. I verified strength by prying hard under a couple of straps to make sure the screws would not rip out easily. If the screws were to pull out, I would use blind rivets to secure the straps instead.

After the dash was mounted back in place I re-installed the dash pad and put everything back together.

No more rattling or squeaking now.

The process of removing the dash pad and dash is too involved to detail here. Here is a look at everything removed for this procedure:

Everything removed for this repair. Quite a task.

A load of parts removed.

An experienced person can probably do this task in one long day. I spent parts of three days to do it all.

Strange to see the car with the whole dash removed:

Entire dash removed as seen from left side…

…and right side.

Technically you can remove the dash with the dash pad/cover in place but it is that much heavier and hard to maneuver if you leave it on.

Update 4/24/14: The dash pad plastic is now so old and brittle almost any disturbance of it is sure to cause damage beyond what is likely already underneath. This one had a lot of big cracks and chunks broken off. In addition it is difficult to get these back into place properly, especially at the right corner above the center vents. I would recommend not removing the pad/cover unless needed for other repairs.

Also, if your air conditioning evaporator is leaking (common problem), this is the best time to replace it because dash removal is required for that repair as well.

When removing and replacing the dash, use caution around the shift knob. I tore this one up by scraping the dash over it. Better to move the knob back out of the way if you can’t be extra careful.

Tore shift knob up when replacing dash. It’s OK because it was crusty and gummy and I have intended to replace it anyway.

$0- No cost beyond some glue, weld and pipe strap, which I had around the house.

The steering wheel on this car is getting really worn and rough. It is uncomfortable to grip it so I need to do something.

Wheel is worn and rough; uncomfortable to grip it.

Tried softening the rough patches with a heat gun but it didn’t flow and even if it did it would be smooth instead of textured for better grip.

So my choices are to replace the steering wheel or cover it. A replacement wheel would be expensive and a fair bit of work so I chose to try the cover approach. Got a gray after-marked cover that looks nice and seems to fit well. It’s a tight fit and took some muscling to get it on but very do-able.

Installed slip-on cover. Looks and feels nice.

Camera flash exaggerates color contrast. In real life, the cover looks darker and is a closer match to the steering wheel.

If this doesn’t work I will try the more expensive lace-on covers that are customized for each car model. They require some time and effort to install but are quite nice.

Since I had been driving this car to work recently, I noticed all sorts of little things that need attention. My commute is at least a half hour so I listen to the radio quite a bit. The speaker in the driver’s door was dead and that became quite obvious in a hurry. It seemed like I lost hearing in my left ear because there was little sound from the radio on that side. This was confirmed by playing with the L-R balance control and F-R fader to localize the dead loudspeaker.

So I investigated to see if it was the speaker or the wiring that was misbehaving. Can’t be the amplifier since I get sound from three other speakers on the left side.

Removed the driver side speaker by prying off the grill and then unscrewing the speaker.

While attempting to disconnect the wires from the speaker, the blue terminal block popped off and two wires with it.

Blue terminal block snapped off when pulling wire disconnects.

It’s hard to get access but I measured resistance across the voice coil wires with a multimeter and found them to read around 4Ω as expected, meaning the speaker coil is OK.

In this design the voice coil wires are soldered to the flexible terminal wires and glued to the speaker cone. While this arrangement may be common, I believe it is a poor design because the mechanically fragile solder joint is constantly vibrating and will probably fail over time. I surmise that one of the joints failed and came loose which is why the speaker stopped working. The other one may have been weak and popped off easily when the terminal block broke away.

Poor solder joints glued to speaker cone. Not a good design.

Flex wires separated from contact solder joints.

It is nearly impossible to re-solder these flex wires to the voice coil because of a small opening and very short leads. And a factory speaker from a salvage car is likely to suffer from the same problem. So a new speaker is in order. Factory speakers are rather expensive so I decided to get a decent quality low-cost after-market replacement. To sound the same on both left and right sides, these speakers should be replaced in pairs, which is how they are usually sold anyway.

Front door factory speaker.

Main specifications are 4Ω impedance and 4 inch (100mm) diameter. Power rating is not critical with the factory amplifier which is relatively weak. There are many different ways a person could replace these but the following is how I chose to do it.

At Crutchfield I found what seem to be decent speakers at a very good sale price ($20 per pair). Customer reviews are generally favorable and most people report a big improvement over factory speakers on most cars. Looking at the one that came out of the car I don’t think they are particularly good; seem to be very cheap and basic. I didn’t want to put much money into these speakers (people often do spend a lot for speakers) but at this price I thought I’d take a chance.

These new speakers are actually coaxial with a tiny tweeter over the woofer (mid/bass) cone. On the 850 the front tweeters are up in the dash pad where the highs reflect off the windshield. So these coaxial replacements will add some highs to the front. This helps because I also tore one of the tweeter cones when working on the dash earlier so it isn’t performing well anyway.

Crutchfield’s replacements are slightly smaller. The speaker cone is 3-1/4″ compared to the factory 4″. The package seems much smaller because the original speaker had a wider metal frame and surround (the flexible part connecting the cone to the frame).

Front side of original and new speaker.

Back side of original and new speaker.

Because it’s smaller, the mounting holes are about 1″ further in, meaning I had to adapt the mounting. It’s much easier to work on this outside the car so I removed the speaker frame from the door.

For mounting adapters I used plastic cable clamps and cut the loop off, then screwed these strips into the bracket. The lower right screw fastens directly to the door so I just used a screw to loosely locate this adapter.

Cut plastic cable clamp just past where it starts to curve and trimmed sharp corners.

With four adapter strips fabricated and installed I marked where the new speaker holes should be and drilled a small starter hole. Then used short self-tapping screws to bite into the plastic adapters.

Adapter strips installed on speaker frame.

New speaker screwed into adapter strips.

I was concerned that these thin plastic strips might not be strong and secure enough but they held together very well even when I pulled on the speaker. I’m confident this adaption scheme will last a long time.

The new speakers have different sized disconnect terminals so I had to cut the original connectors off and splice in to the wiring adapters provided with the speakers.

Spliced in adapter wires to match new speaker terminals.

Now I could install the speaker frame back into the door and secure that fourth (lower right) adapter strip.

New speaker adapted, installed and wired, ready for sound check.

Ready for audio check and it worked very well; sounds clear and loud and has a lot more high-frequency response with the coaxial tweeter built in. Not audiophile grade speakers but to me they sound slightly better than the original speaker.

Snapped the cover back over the speaker and we’re ready to do the same for the right (US passenger) side speaker. Even though that speaker still works, it should be replaced to match sound quality.

Other people might want to upgrade their sound system in the same situation or just get higher-quality speakers. I was more interested in being cheap but keeping sound at least as good as factory speakers.

Update 4/10/14: When I replaced the passenger (US right) side speaker, I tried doing the work in the car without removing the speaker frame from the door. Turns out this works fine and a little less work.

New speaker on right side installed without removing frame from door. Works well.

Check engine light came on with trouble code P0455 (evaporative emissions large leak). Reset it and made sure the gas cap was tight on the fuel tank but the error came back. This indicates a significant leak in the fuel tank or hoses or evap components leading from the tank to the intake manifold. For some months now we have had random large and small leak codes pop up but we could reset them for awhile. Now it’s permanent so hopefully I can find a problem.

Began sniffing around with my combustible gas leak detector (a useful tool for locating fuel leaks in a post dated 1/19/14) and registered a big leak under the car around the fuel filter.

After lifting the car to crawl around and inspect the area, I found that the leak was not at the fuel filter or fittings but just above the filter towards the rear. Looking carefully I spotted a separated line:

Evap line separated from roll-over valve.

The rubber coupling from the roll-over valve to the evap line going towards the engine area had deteriorated and actually separated.

Hose separation at roll-over valve just above and behind fuel filter.

Evap line separated from roll-over valve.

This is sure to trigger the large leak error because the fuel tank is wide open to the roll-over valve via the fuel evaporation collection tube.

Started repair by removing the roll-over valve from the fuel pump bracket to gain access. Just one bolt holding it in place. Here I discovered that the hose on the inlet side of the valve was also cracked and nearly separated, so both ends need repair.

By the way, this is one of the dirtiest jobs I’ve experienced working on this car. Manipulating the roll-over valve and tubing requires working up under the car and years of dark crud flaking off and landing in your face and all over your body. Even wearing safety glasses I got black flakes in my eyes so plan for a mess.

Here is where it gets interesting. The plastic evap tubes measure 7.5mm and the roll-over valve nipples are 6mm, so they are unequal in diameter. The coupling hose has two different diameters:

Broken coupling hose shown to demonstrate tube size difference.

I wanted to avoid buying the factory parts to save time and cost so for this car I used some 1/4″ (6.3mm) ID heater hose from an auto parts store.

1/4-in hose is loose but workable at roll-over valve end and very tight at evap tube end.

The hose fits reasonably snugly on the roll-over valve nipples. A 6.5mm ridge or barb helps the fit, and a little petroleum jelly smeared on the nipples helps make the seal.

It’s harder pushing the undersized hose onto the plastic tubes but I was able to get about 1/2″ of engagement. A little petroleum jelly helps lube it and twisting the hose also helps force it on. It’s difficult to get arms and hands into the area of the tank tube so that was challenging but I managed to push the hose onto the tube.

Pushing hose onto tank tube is difficult but can be done.

They certainly don’t pull off easily but I would have liked the hose to slide over the tube a little longer.

Cut the tubing in lengths to roughly match the original coupling hoses. Slipped both ends onto the valve and then bolted it back into place.

All put back together using 1/4″ hose.

Time will tell for this one but it should work. Have to drive it around for a while to see if an evap leak code comes back.

$0.69 for hose (1ft@69 per foot)

My 850 sedan has frequent evap leaks as well and I suspect the same thing is happening to that car. Based on my experience using straight hose I decided to bite the bullet and buy real Volvo coupling hoses for the other car. Replacement procedure is the same except that it is easier to slip the hose onto the tube ends.

Update 4/9/14: Replaced both hoses on the sedan using the factory parts this time. Rear hose coming from fuel filler neck was badly cracked and split. Front hose was crusty but not obviously leaking.

Sedan hose split at rollover valve on rear side.

Factory coupling hose with two different tube sizes.

With these factory hoses, the plastic tubing end was now easier but the roll-over valve ends were harder to slip over. This is opposite of when I used the straight 1/4″ tubing as done originally.

New hoses installed both sides of roll-over valve.

$35.01 for two Volvo tube couplings

By the way, I plan to write up a posting on the evaporative emissions system and how to isolate and check for leaks in it. It will also cover how the car determines faults in the system.

Technical Notes

Original rubber parts including most hoses on cars this old (newest model 850 is now 17 years old) are guaranteed to be bad or on their way there. This is because they slowly dry out and become hard and brittle, losing their elasticity. Heat, chemicals and vibration contribute to the problem. Point being that the vacuum and evap hoses or elbows on these cars will all likely need to be replaced. One might do it proactively or just deal with them as problems occur.

Counter-intuitively, the roll-over valve is not part of the fuel supply line. It prevents fuel in the tank from flowing towards the evaporative emissions charcoal canister in case the car is upside-down or on its side, in which case the evap tube might be directly in contact with liquid fuel. Basically a safety device, cheap and simple way to minimize fire risk.

Recent activity on front seats in both of our 850s inspired me to post a word of caution when working on the seats. Most 850 front seats have a side impact protection system (SIPS) which is really just an air bag that pops out of the seat. In theory if the car were struck from the side hard enough to deform the front seat bottom, the air bag would deploy and provide some cushion against injury to the torso.

Unlike the airbags in the steering wheel and front passenger dashboard panel, these SIPS bags are not operated by electronics using a deceleration sensor. Instead, they are pyrotechnic devices that work physically. When the trigger is struck the cushion deploys instantly. No electronics involved.

1-Sensor Unit, 2-Firing Circuit, 3-Cushion Module

Note how air bag pops out the back towards the front, protecting occupant’s ribcage.

There are a couple of interesting videos on YouTube where a seat air bag is deliberately triggered to demonstrate exactly how it works: Video 1 , Video 2 It’s not obvious from the videos but bag deployment is loud, like a shotgun blast.

Now to the point of all this. When working on or around the seats, if there is any chance of striking the sensor accidentally, you should install the special safety device designed to minimize probability of unintentional deployment. If your face was near the seat you could be seriously injured or suffer hearing loss when the bag explodes.

Volvo considered this hazard and so provides a safety device under the front seat side pocket.

Orange safety clip stowed under seat side pocket.

The seat pocket assembly is removed by moving the seat forward, lifting the rear up and then towards the front to release, then lift out.

Risk of accidental air bag deployment if sensor is struck hard enough.

Safety device minimizes risk of unintentional air bag deployment when working on or around front seats.

Obviously you need to remove the safety device when done working on or around the seats and put the seat pocket back in place.

Technical Notes

SIPS Description and Operation

General Information
The SIPS bag is activated by certain side impact collisions and is designed to help increase protection to front seat passengers.

The SIPS bag is being introduced as standard equipment in some markets and as an option in others, beginning with model year 1995.

The SIPS bag system consists of three main components:

Sensor unit

Firing circuit

Cushion module

Sensor unit
The sensor unit is located in a sensor mount at the outer end of the forward SIPS tube. The mount is the part of the chair that protrudes the most toward the inside of the door.

A pressure plate is mounted forward of the sensor unit. In the event of a collision, the pressure plate transfers the force from the inside door panel to the sensor unit.

Firing circuit
The pyrotechnic firing circuit runs through the seat back and under the seat cushion.

The firing circuit consists of two tubes coated on the inside with a pyrotechnic material. When triggered, the signal is transmitted as a shock wave.

The tubes are covered with a black protective sleeve to protect them from mechanical damage.

SIPS-bag cushion module
The cushion module is located on the seatback frame to help provide protection to the driver/passenger where the rib cage is closest to the inside door panel.

Cushion
The cushion, made of silicone-coated polyamid fabric, is folded under a cover. When inflated, the cushion has a volume of about 12 liters (0.4 cubic feet).

Gas generators
Two gas generators inflate the cushion. When activated, the gas generators produce a harmless gas which inflates the cushion very quickly.

Functional description, general
The SIPS bag is a separate system in each front seat. There is no connection between the two SIPS bags. In the event of a certain side impact collision, the SIPS bag will be activated only on the side of the collision. The sensor unit is a pyrotechnic impact sensor, which will be activated only if it is struck with an impact that causes the deformed door to hit the sensor with a speed of about 2 m/s (6.6 ft/sec). The system is calibrated to avoid unnecessary activation such as by a blow to the door or a light impact with a stationary object.

The pressure plate will deform the aluminum cover, pushing a firing pin and releasing the ignition charge. The ignition charge creates an impulse which is transmitted through the firing circuit as a shock wave. When the shock wave reaches the cushion module, it ignites the powder charge in the gas generator.

When released, the gas blows through a firing chamber tube and into the cushion. Activation of the first gas generator occurs immediately and the second is activated after a delay of about 3 milliseconds. The delay is designed to maintain the pressure and volume of the inflated cushion for an adequate time.

During inflation, the cushion breaks open the cushion module cover, rips open the chair upholstery seam and pushes out to inflate to its full volume. The cushion inflates toward the door panel to help protect the passenger’s rib cage during the collision. There is a vent though a hole in the cushion, so it will collapse slowly enough to act as a brake on the driver/passenger.

There is no diagnostic system or warning lamp connected to the SIPS bag.

The SIPS bag is available only in cars equipped with the SRS system, and it is always installed in both front seats.

Being lazy like most people when it comes to maintenance, I let the leather seats deteriorate in my 850 sedan. Small cracks became large ones until they tore open. Once that happened the holes just got bigger and even the foam cushion started to wear off.

Driver seat leather cracked, torn and worn mainly on bottom.

Seat cushion foam is even breaking off.

Common problem on cars this old. Cloth and leather take a lot abuse, mainly when climbing in and out of the car since you pretty much have to slide across the seat to get in.

Besides being ugly, it was actually uncomfortable to sit on this, especially wearing shorts. So I had to do something to fix the problem Being a solo occupant 90% of the time, the other seats are still in good shape so this is a one-seat repair.

Tried using the cheap seat covers which look OK but the bottom pad is loose and just slides around, making sitting down a real chore. Gave up on this idea quickly.

Simple cushion would work to cover damage if bottom pad could be fixed in place.

Tried custom-fit covers which take a fair bit of effort to install. There were straps all around but they really didn’t stay put on the bottom and they were fairly thin anyway so I could still feel the damage underneath. These went into the trash as well.

These fitted covers didn’t work well for me.

Seems like re-covering is the only viable solution. Purists will want to recover the seats with leather but it is very expensive. Like $500 per seat plus a lot of work on top of that.

While having the red wagon project car headliner replaced, I inquired about reupholstering the seats. The shop could do it for a reasonable price and it would look good, so I was told.

So months later when I was ready to fix this white sedan leather seat, I removed the seat and took it to the same shop for re-covering. To save a lot of money we went with vinyl material.

Matched the color and texture as best we could and I left the seat there for a few days. They removed the damaged seat cushion and seat back front leather and replaced those pieces with vinyl, leaving the original leather on sides and backs of seat. It was stitched in place to look like original.

I was very pleased with the results. Looks very nice and only a slight color variance.

New vinyl seat faces look great.

Seat back re-covered with vinyl to match leather.

Shop even repaired the torn foam seat cushion.

Slight color mismatch is not bad and looks closer in sunlight.

Re-covered seat installed in car matches rest of leather seats well.

View from passenger side.

My only complaint is that the vinyl is not as smooth as the leather when sliding into the car so my large posterior catches a little. It may wear smooth over time.

Long-term durability is unknown at this point but I really doubt this car will go another 10-15 years anyway.

As mentioned in task #87, while checking for coolant leaks I discovered that the heater core was leaking. I fixed the bigger leak at the upper radiator hose and left this heater leak for later. It seemed just a minor nuisance where I could keep topping off the coolant level, plus my impression was that replacing the heater core was a big job.

Since then I’ve come to realize that replacement isn’t terribly difficult or time-consuming. More importantly, I learned the hard way that a leaking heater core can be a real safety issue because it will fog up the windows.

This is a very common problem on 850s– probably on every car from the factory because of a poor design in the heater core itself where the plastic frame is not properly bonded to the heat exchanger. After ten years or so (and all Volvo 850s are now at least 16 years old) the heater core will leak a little coolant. Not too much, but enough to be a situation that needs attention.

Even if you are willing to just keep topping off the coolant, it’s a real problem because if you ever use your heater a leaky core creates a fine aerosol of coolant (water and antifreeze) which deposits a moist, oily film on the windows.

Leaking heater core puts a moist, oily film on inside of windows.

This then attracts dust and such in the cabin which just obscures the windows even more. Eventually it’s hard to see out the windows, particularly at night and when the sun is low. Poor visibility is a real safety issue and is what convinced me I needed to fix the leak. It took several passes with cleaner and rags to get the windows really clean and there is a lot of glass on a wagon. This film is also being deposited on the passengers and everything else in the cabin. :(

You will probably first detect a heater core coolant leak with your nose. When any heat is turned on some air flows around the heater core and the vapor from the anti-freeze chemical moves into the cabin. Most of us recognize the unique sweet odor of ethylene glycol in the coolant. If you’re not sure, just remove the coolant reservoir cap and give it a sniff. If you smell the same odor inside the car with heat on, you’ve got a leak.

Confirmation of a leak is coupled with an observable drop in coolant level in the reservoir. The heater core is located forward of the transmission/gear shift lever under the dash just above the floor. Access requires removal of the dash board lower covers and then pulling back carpet and removal of plastic covers under that.

When I opened up the panels on this car, I found a wet spot on the inside of one of the panels and shiny wet spots around the base of the heater box.

Access to these screws is somewhat awkward. It helps to push the seats back, put a cushion on the floor, lay on your back working up and have a good work light.

5. Pinch off both heater hoses on engine side of fire wall to prevent draining engine coolant into the car.

Both hoses between engine and heater box pinched off.

Hose access improved by removing heat duct to air cleaner.

6. Pull evaporator drain fitting out of hole to provide space for removing the heater box.

AC evaporator drain tube pulled up and out of way.

7. Unscrew tubes from heater box.

Single screw secures tubes to heater core.

8. Pull heater core and tube block apart. Be prepared with rags or towels for quite a bit of coolant leakage (residual in the hoses and tubes plus inside core). It may take some prying and effort to separate.

Separate core from heater tubes.

9. Rotate heater box back and out the RH side (US passenger).

Rotate core out of heater box and out passenger side.

Note access to the heater box may be slightly different on earlier model 850s but the general idea is the same. On models with manual transmission there is also a gear shift cable passing under the heater core to work around.

Heater core is now out of the car and can be worked on in a convenient location.

10. Remove screws holding the heater core in the frame and pull the old core out.

Four screws on end hold core in frame.

Core removed from frame.

Wet spots at top (and bottom) of core typical result of plastic separation from aluminum tubes.

Now ready to install new heater core. While many people insist on using factory heater core replacements, the design is still flawed and will happen again. They are also a bit expensive. I chose to go with an after-market part that claimed to have an improved design. It also comes with two new O-rings for sealing the tubes and is at a very good price on eBay. This is likely a knock-off of a better part but they claim that their design fixes the expansion problem by crimping the tubes onto the plastic tanks. If it lasts five years or more I’ll be happy; not sure how much life the car has left in it.

New core at right is an exact match to old one on left.

New core crimps tubes to plastic to avoid separation problem.

This new core came with foam strips installed. If yours doesn’t, you would have install new foam strips to match old core.

11. Clean up the frame to remove oil and dirt. Disintegrating foam strip leaves a lot of debris behind. It also would not be sealing well, meaning some air flow through the heater box will bypass the heater core, reducing heat efficiency. New foam will seal better and give better heating.

Old core foam strip was disintegrating and really gummed up the frame.

Cleaned up core frame before installing new part.

12. Put new heater core in frame and screw in place.

New and improved heater core installed in frame.

13. Remove O-rings from ends of tubes from firewall and replace with new ones. If your tubes are corroded they should be cleaned up before installing O-rings. If your pipes are steel (older models) consider replacing with newer aluminum tubes. Always use new O-rings because the old ones will be dry, hard and not pliable.

Old, dry and hardened O-rings were removed.

Tube ends were slightly corroded. Cleaned up the surface with strip of emery paper.

New O-rings installed with a bit of petroleum jelly to improve seal and preserve elasticity.

21. Push carpet back into place on both sides. It’s probably a good idea to let the car air out for several hours (windows open) to evaporate much of the spilled coolant from inside the cabin.

22. Install lower dash panels.

I’m going to wait a week or two before cleaning the inside windows again. There is likely some residual coolant in the ducts and air vents which has yet to be pushed into the cabin. Once it’s dried out we can clean the windows for good.

Now I get to do this again on my 850 sedan which also has a heater core leak, just not as bad (no coolant loss and no foggy windows but antifreeze odor with heater on).

$39 for low-cost “improved” design heater core

Technical Note

The heater core is essentially a small radiator, much like the big one in front of the engine. Hot coolant from the running engine flows through the core and air flows through the fins where the heat from the coolant is transferred to the air.

On Volvo 850s coolant flows constantly through the heater core; there is no shut off valve or regulator. Heat into the cabin is determined by temperature settings on the climate control. This regulates air damper position to direct more air through the heater core as you increase temperature. So while hot coolant is always circulating through the heater core, it does not exchange heat to the cabin until the operator selects some heat.

I’ve been driving this red wagon project car to work while my 850 sedan is having the driver’s seat re-covered.

Besides having an automatic transmission on the wagon (which makes for a little confusion), another difference I noticed is the lack of a better cup holder. I have a simple cup holder added to my sedan that accommodates a larger cup in a better location and I miss having this feature while commuting in the morning, breakfast smoothie in hand.

So I picked one up and added it to this car and the girls will probably appreciate it in the future as well. Not worthy of a numbered task but thought I’d share this idea with others since it’s probably a common complaint about this car.

The stock 850 has only two useful cup holders which pull out in the center console.

Stock pull-out cup holders are small and obscure window controls.

They provide for only smaller cups and they are in the way of the window and mirror controls.

Years ago I discovered that one of these large cup holders with hooks works well on the console forward of the gear selector. They are designed to hang from the door at the window but on 850s that surface is too wide for these cup holders to attach.

If you hang it on the side of the console on the passenger side, the driver can still reach it and it stays put as long as the ashtray is open. The ashtray keeps the holder from bouncing loose or moving out of place easily.

Large cup holder hangs off console, held in place by open ashtray.

On the driver’s side it would likely get kicked too much. If you really wanted it to be secure, you could put a screw through it into the plastic console but that would leave a hole.

If your 850 has the keyless entry feature which allows you to lock and unlock the doors from a short distance using a small transmitter on the key chain (fob), here is the procedure for programming the car to respond to the remote control.

This is valid for Volvo 850 in model years 1996 and 1997 that use the remote/key fob shown below. I have seen one reference that it applies to 1995 cars as well, so you really need to make sure you know what you have. For earlier 850s there is a different remote but the procedure seems to be the same.

Volvo 9442982 Transmitter

1. Gather all the transmitters (key fobs) you want the car to recognize and keep them handy in the car with you. You can program up to four remotes per car. Make sure they have fresh batteries or are known to work.

2. Start by sitting in the driver’s seat with doors closed (and from experience, tail gate closed and doors locked on wagons.) If it’s hot and uncomfortable inside, you can roll the windows down for some relief.

3. Insert key into the ignition switch and quickly switch back and forth between positions 0 (off) and II (not III which will start engine) as quickly as you can five times.

4. Red light on top of dash pad near windshield should blink on and off with key still in position II.

5. Quickly push either button on each remote that you want the car to learn. You have around 10 seconds per remote for this teaching input. Light will glow steady for a couple of seconds when it recognizes a transmitter.

6. Switch key back to 0 (off) and remove key.

7. Test each remote function by unlocking and locking to verify they were all learned.

Repeat as needed if something doesn’t work quite right or if you were too slow.

Procedure from the 1997 Volvo 850 Owners Manual

Programming a transmitter

If you purchase additional transmitters (max. 4), they must be programmed to function with your alarm/remote keyless entry system. To do this:

Make sure all doors, hood and trunk/tailgate are closed.

Turn the ignition on and off 5 times within 10 seconds. On the fifth try, leave the ignition on.

Press either button on the transmitter.
NOTE: The first transmitter must be programmed within 15 seconds, the others within 10 second intervals. When the alarm system accepts the codes from each transmitter, the LED on the dash will glow steadily for several seconds.

Switch the ignition off and test the transmitter(s).

Practical range of the remote transmitter is 10-15 feet (3-5 meters) per owners manual. I have observed slightly greater range but it’s not a long distance.

Replacement transmitters are found on eBay in the $40-70 range used and $80-100 range for new. Factory new part from volvopartswebstore is around $82.

If your 850 does not have this keyless entry feature but you’d like to have it, I posted an entry on retrofitting it quite easily at fairly low cost.

I have been spoiled with my daily driver, an 850 sedan that has keyless entry. This allows me to lock and unlock the doors from a short distance with a small transmitter that is attached to the key ring (remote key fob). So when I drive this 850 wagon project car it’s a constant adjustment to think, “Oh, I have to put the key in the door lock and turn it–which way again?”

This made me wonder how easy (or hard) it would be to retrofit keyless entry to this car or any other 850 lacking the feature. Turns out, it’s quite easy. The wiring is all there, only a few components are missing. At the very least, all you have to do is remove an immobilizer jumper relay and insert an alarm relay to make it work.

Looking at the difference between the cars, I see that this red wagon has a brown 210 relay while the white sedan has a gray double 210/211 relay.

Brown 210 single relay is just a jumper to bypass immobilizer when alarm relay is not installed.

Gray 210/211 double relay adds keyless entry and alarm feature.

To prove the theory, I removed the alarm relay from my sedan and installed it into the wagon. Then tested the key fob remote control and the locks popped up and down like they should. So then I knew it was just a matter of putting another one of these relays in the red wagon and programming it.

On 1997 models the relay is located under the (USA) driver’s side panel, tucked up above the hood (bonnet) release lever. Three screws to remove and this panel drops out.

Remove access panel below steering wheel to locate alarm relay.

Pulled a couple of these 210/211 gray alarm relays from wrecks at a salvage yard months ago when we first started this project, thinking they would be useful some day. That day has arrived.

Alarm relay is also the keyless entry receiver to activate door locks when the remote buttons are pushed.

Installed one in this project car by pulling the single brown 210 relay and inserting the double 210/211 relay. The 211 side fills a socket that is empty without the alarm relay.

To retrofit keyless entry, simply unplug the brown 210 relay and install the gray 210/211 double relay in its place.

Plugging the relay in is awkward and somewhat difficult working up in that tight space and having to contort your body just to get your arms in the right position. There is also a fat bundle of wires right in the way that you have to work around/through. But with a little fussing and practice, it’s not so bad.

To program the new relay to the desired remote transmitter, you turn the ignition switch (key) from positions I to II five times rapidly, then press the lock button on the desired remotes (up to three), then turn key off. Doors must be closed and locked for this to happen. A more detailed post on this procedure is found in the next blog entry.

The remote/key fob transmitter is Volvo part number 9442982 and looks like this:

Volvo 9442982 Key Fob

For now I will use the two remotes we have that work on the sedan (both fobs will work on both cars) but may get one or two used on eBay for the girls to have for their own at a later date.

Part 2 of this retrofit will involve adding an alarm indicator to the dashboard and an alarm horn under the hood. Neither are necessary for keyless entry but the red LED is nice to have for programming as well as a deterrent to would-be thieves. The alarm siren is also nice to scare off somebody who breaks in and as an attention getter using the remote key fob panic feature.

Note: On older model 850s the receiver/alarm relay is a different box in a different location, I believe. From what I gather, it’s a flat black package mounted behind the glove box liner to one side. I don’t know if a retrofit is as simple for older models but I would not be surprised if it worked much the same, just different packaging and location.

Summary: Intermittent events where engine would not crank became more frequent and finally the starter quit working altogether. Diagnosed by eliminating likely causes (battery, battery cables, neutral switch) and then tested by applying voltage directly to starter control terminal. Finding the starter dead, it was removed and replaced.

Details: Recently we experienced several instances where the engine would not start. Turning the key to the start position resulted in just a clicking sound from under the hood but the starter would not turn. Sometimes it would work and sometimes not so once again it’s a frustrating intermittent problem.

1st thing to check when the car won’t start is the battery condition because this is the main cause of starting problems. Connected my analyzer and the battery checked out 100% perfect (voltage and capacity).

Then looked at battery terminal connections which were tight and clean. This is the 2nd most common cause of starting problems. Followed the fat red battery positive terminal wire down to the starter and it was tight and clean, as was the fat blue negative wire to the engine block.

The 3rd most likely cause of no-crank problems is a clutch switch (manual transmission) or Park-Neutral Position (PNP) switch (automatic transmission) being open. 850s do not have clutch switches from what I can tell; they were added to later model S70s, I believe. This car has an automatic transmission so it does have a PNP switch which is known to fail with age. Running the shifter up and down to freshen up the switch contacts did not help. Besides, I could hear the starter solenoid clicking which indicates that it made it past these interlocks.

A 4th possibility is a defective ignition switch but that was replaced in the past year and as mentioned the solenoid was clicking, indicating that the circuit was working.

A 5th cause of starting problems is arguably more or less likely than the others. This is the immobilizer or alarm relay which is an anti-theft feature that prevents the car from starting if the doors are not properly opened with a key or keyless remote. It was not an issue here.

Once I got it to start more frequently I noticed that there was a delay from when I turned the key to when the starter would crank. That indicates a sluggish starter solenoid, as if it was weak. Then I noticed that after releasing the ignition key from start position the starter would stay engaged for a half second or so (that whirring sound you hear when you are still cranking the starter after the engine starts running on its own). That also suggested a lazy solenoid or weak return spring or sticky solenoid plunger, all of which are starter problems.

All these diagnoses point to the starter itself so I started testing it. One nice thing Volvo did with the 850 (and likely other models) is include a handy starter diagnostic connector up near the brake master cylinder. This female blade socket makes direct connection to the starter solenoid control terminal which receives +12V when the key is turned to the start position.

Starter test port 17/1 location.

Test port near ignition coil and LH strut tower.

Actually, not quite a direct path. The test connector still goes through the PNP switch on cars with automatic transmission after this point so if you want direct connection to the starter solenoid, you’d have to connect at the solenoid. Manual transmission does go directly there. See wiring diagram for details.

Wiring Diagram

I made up a test wire by crimping some wire to a standard 1/4″ male blade terminal. The male tab mates nicely with the test socket and gives us a handy connection to measure resistance (old starter solenoid measured high at 3.2Ω, new solenoid was 0.5Ω), voltage or apply voltage. Instead of touching the other end of the wire to the battery positive terminal, I clipped a squeeze switch in line to get better control.

Test wire connected. Far end connected directly to battery + or through switch makes starter operate as if turning they key.

Using the switch allows me to work without an assistant to turn the key and with the first pair of quick switches the starter would crank but then the starter stopped turning and I would hear a metallic clunk when activating the switch. After several of these, I could get just a small click from the solenoid. So clearly the solenoid and/or the starter were failing quickly.

Access to the wiring terminals is made behind the snap-on cover. Be very careful with metallic tools down there; a short to anything metal will give full battery energy spark.

Pull this cover off to access starter terminals. No tools needed; just snaps on/off.

Unplugged the control (start) terminal and measured voltage with respect to the engine block. When energizing the test port I measured +12.5V so I know the starter is getting proper control voltage. That clears up any doubt that the solenoid or motor were bad.

Measured control voltage at the disconnected wiring terminal. +12V here with no start means a bad starter or solenoid.

Tried tapping on the solenoid and starter to see if this would make it work again. Don’t laugh, this often gets a failed starter to work one or two more times if something is stuck or if the motor is in a dead spot. No good and so now the intermittent problem has become a permanent problem. Clearly the solenoid or starter motor has issues and the whole thing needs to be replaced.

Replacing the starter is not difficult but you do have to remove several things to gain access.

First you disconnect the battery negative (-) terminal after verifying you have the radio code. Then you remove the control module cooling pipe, air duct to air cleaner, fan shroud assembly and relays and vacuum valves mounted to it, which requires disconnecting various cables and hoses. Finally remove throttle pulley cover and solenoid cover if not already done.

Various air ducts and throttle cover removed for access.

Fan assembly and associated wires and hoses removed for access to starter.

Now we can remove the starter itself. Start by unbolting or unplugging all wires from the starter.

Cables disconnected from starter solenoid.

Then remove three bolts holding the starter to the engine block and lift the starter out. Shop manual and other procedures do not mention unfastening this harness clamp…

Harness clamp must be removed to get wrench on lower bolt.

…or removing the throttle body intake pipe, but both had to be done for access.

Tried to unscrew the solenoid from the starter to inspect the guts but could remove only one of three screws, even using an impact driver after spraying penetrating oil, so gave up on doing an autopsy. Wish I knew what was going on inside there.

While many people insist on factory parts only, like several other tasks on this project I choose to save money by using a high-quality re-manufactured starter.

Shiny new starter.

I’m saving hundreds of dollars and I doubt that the quality difference will be noticeable in the short term. Maybe 15 years out but I don’t think this car will still be around that long. Besides, my experience with reman parts is that they often are factory parts that have been cleaned, renewed and tested so are as good as new. This one had the Bosch ID stamps on it so is likely mostly factory parts.

As for the solenoid, I believe that there are two coils: one higher current (lower resistance) to pull the plunger in and one lower current (higher resistance) to hold the plunger in after disconnecting the high-current coil. Since the old bad coil measured 3.2Ω and the new one measured 0.5Ω, I’m guessing that the high current coil was open or the disconnect switch was stuck open. Either way, it would leave only the holding coil in the circuit which is not strong enough to pull the solenoid closed, at least reliably.

New starter is installed in reverse of the removal procedure.

New starter bolted in place…

…and wires attached.

Put all the ducts, fan, hoses, relays and covers back in place and ready to check after reconnecting the battery negative terminal. Key in and it starts right up. No surprise.

$140 for an remanufactured starter.

Technical Notes

The main parts of a starter are the motor and the solenoid which are combined in one assembly. The motor is just a high-torque, high-current DC motor that is strong enough to spin the engine.

The solenoid does two important jobs and is often the culprit with a bad starter. First it switches the battery connection to the motor winding, like a big high-current relay or contactor. Second it pushes the pinion gear out to engage the engine flywheel teeth so that the spinning motor is coupled to the engine for starting and releases it once the engine is running. These two things are accomplished in one linear motion by an electromagnetic field from the solenoid coil.

This is sort of an appendage to post #82 regarding fuel pump replacement. There are three issues that I feel worth sharing with other DIYers.

First is that when you remove the fuel pump for replacement or rebuilding, it is important to thread the big plastic pump retaining nut back on the tank unless you quickly put the pump back in and secure it. For whatever reason the male threads on the tank (Volvo calls it the collar) tend to expand or swell so that it’s hard to thread the locking ring back on if it has been off for some time. I learned this the hard way when replacing the pump on this car in post #82 where I rebuilt the pump which took some time. Since the nut was off the tank for some hours, I had a really difficult time getting it back on later. The Volvo shop manual, Alldata DIY and the Haynes manual all have notes about doing this.

Second is to consider your fuel pump gasket when removing the fuel pump. In one case where I replaced the fuel pump in my 850 sedan with a high-quality aftermarket pump, it came with a new gasket (rubber seal between the pump flange and tank). However, that aftermarket gasket was slightly under-sized so it would not stay in place on the tank rim and it would leak vapors because the sealing surfaces were not aligned. Since then it has caused small–and sometimes large–evap leak codes. When I installed a new Volvo factory gasket, it sealed properly and the leak went away. I presume the same could happen with an old, dried gasket. All the references indicate to use a fresh new gasket.

Third is that cheap petroleum jelly from a drug store is recommended to lubricate the new gasket to keep it pliable and give a better seal. I had used plumber’s silicone grease which may be OK but petroleum jelly makes more sense. I mean, hey– it’s petroleum based and we’re using petroleum fuel here. Also recommended for the push-on fuel fittings for the fuel pump. I dry swab the inside of the fittings and smear jelly on the metal connectors of the fuel tank. This gives a better vapor seal, renews old dried O-rings and makes pushing the fittings on a little easier. Now that I think about it, jelly would be good to apply to the fuel filter fittings as well since they have the same push-on O-ring seals.

Long post so I’ll give an executive summary first:Occasional random events of engine quitting while driving caused me to narrow down possibilities. Focused on coolant temperature sensor and learned that a loose connection here can cause surging and stalling. Discovered that the sensor was aged and out of spec so needed to be replaced. More importantly, the connector had major issues. Replaced the temp sensor and replaced the connector contacts for reliability plus added a missing connector bracket. Hoping this cures the engine stalling problem.

Now for the details: For months now we have experienced the nuisance of having the engine just die while driving slowly. It occurs infrequently and these intermittent problems are the worst kind to solve. So far it seems to happen at half throttle; not at idle and not at highway speed. No error codes on the ECU but when the engine quits the instrument cluster lights up with all those warning lights. No real self-diagnostics to use here. Car will usually start right up after these incidents.

Idle stalling problems are often caused by a dirty throttle body or a gummed up idle air controller but this is not a problem at idle. In 850s stalls are frequently due to fuel delivery problems (fuel pump, fuel filter, pump relay.) However, the pump was recently rebuilt, the filter is less than one year old and the relay was renewed so these are unlikely causes. Ignition (spark) is also suspect although this is more likely to throw an error code which we are not seeing.

I was leaning towards an intermittent sensor to explain this problem. Two sensors are used by the ECU to adjust fuel injection into the cylinders based on various conditions. First is the mass air flow (MAF) sensor. This one was new when we got the car and it seems to behave normally. The other is the engine coolant temperature (ECT) sensor. This one seems to be original and is turning colors with corrosion plus these are known to fail with age, coolant quality and overheating incidents.

The ECT sensor is sort of hiding under the upper radiator hose at the thermostat housing.

ECT sensor located at thermostat housing under upper radiator hose.

Looks a bit crusty now and has been there a long time. Some people recommend they be replaced with the thermostat although I have never done so. Flaky sensors are known to cause various problems from hard starts to poor fuel economy to mystery stalls such as we are experiencing now. At any rate, since these are known to be problematic and this one is apparently old (likely factory original), I started investigating it.

There are resistance and voltage specifications for a proper functioning ECT sensor. It is basically nothing more than a two-terminal resistor which changes value corresponding to temperature. See tech notes below for details. I unplugged it to check the cold resistance and was surprised to discover that the connector on the wiring harness side was broken and falling apart. The two contacts were loose and not being retained in the connector housing. The contacts were also fairly corroded. I know that poor electrical contacts can cause all sorts of problems, particularly intermittent failures where they work most of the time but occasionally lose contact. So this automatically became my main suspect for the stalling problem.

Socket contacts loose and corroded are a huge problem.

Sensor pin contacts properly retained in housing but also corroded.

I suspect that the sensor signal cuts out intermittently with vibration while driving, which is interpreted by the ECU as a cold engine, which responds by dumping more fuel into the intake to a warm engine. That gush of fuel effectively chokes the engine and it dies. This was confirmed experimentally by running the engine, then while pulling the connector apart, the engine would suddenly surge a few times. When plugging back together again, the engine died, just like the problem we are experiencing (although this experiment was at idle). So the theory that a bad ECT sensor can cause the engine to surge and/or stall is proven true. No error codes occur so it may be that intermittent contact is short enough to cause a surge but not long enough to register an error.

Cold resistance was measured with a multimeter and showed about 5200Ω. Compared against a new sensor which measured 2400Ω and the sensor in my 850 sedan which measured 3000Ω, this cold value is quite high. Factory spec is 2800Ω at 68°F (it was slightly warmer than this so the new part was right on spec). Ran the engine up to stable temp on the instrument gauge and checked the resistance at this level. Measured 300Ω compared to my sedan at 200Ω and subsequent reading of 212Ω with the new sensor installed. Factory spec is 150Ω at boiling, which we are just under so the value should be in the 150-200 range. This old sensor is about twice the resistance it should be at both hot and cold.

I also have a nice code reader which will display the real-time data stream of monitored parameters. This old sensor runs hot and stable at 180°F compared to my sedan at 200°F; not too far off but seems a little low, which is consistent with its higher resistance.

Data stream coolant temp parameter stabilizes at 180°F.

All these diagnoses lead to two conclusions: First, the ECT sensor is old and high in resistance and operating values. Second, the bad connector is quite likely causing intermittent connections to the sensor due to corrosion and unsecure terminals. This intermittent connection can cause surges and/or stalling engines so both the sensor and the connector need to be replaced.

To remove the old sensor requires that the radiator be partially drained of coolant, then the thermostat housing removed for access to the sensor itself.

Unscrewing the ECT is a pain because there is no room for a standard 19mm wrench. Factory procedure is to release the pin contacts from the connector to allow the cable to pass through a box-end (ring) wrench. Polarity of the wires does not matter so there is no need to orient them when finished if this is done.

Sensor connector removed to allow box end wrench to slide over wires. You could also just snip the wires if you’re throwing the sensor away.

A bit tricky to remove connector housing. Basically pry out on sides to release latch then flip end up. Hinged near middle of connector.

19mm box end wrench slips over wires to loosen/tighten sensor.

New sensor compared to old one.

Installed new sensor with fresh crush washer then secured the thermostat housing back in place and snapped the sensor connector back on the wires. Polarity doesn’t matter (both wires are black).

New sensor installed with thermostat housing back and coolant refilled.

Then added fresh coolant back in.

To repair the loose connector with corroded sockets I gave up trying to identify a new part number to order so went to a Volvo junkyard to snip one off of a scrapped 850. But after looking at several, they all had some degree of corrosion and loose contacts so this is obviously a common problem that all 850 owners should be aware of. I took the best connector I could find; the contacts were crusty but they were secure in the housing.

Old contacts are corroded and plastic bushing is hard and cracked so contacts are not secure.

Found a website where a guy sells Volvo wire harnesses and connectors and relays and other interesting things. Nothing specific to 850s but he sells connector bullet terminals with new bushings that are pre-crimped on 24″ wires. Ordered a couple of these to try out and they fit fine in the old connector housing so I basically repaired the connector with new contacts by splicing them into the engine wiring harness.

Here are the female bullet contacts I ordered from Dave’s Volvo Page. Choice of colors.

Pre-crimped terminals fit perfectly in connector housing.

Verified good connection with sensor before installing either parts.

Solder spliced each wire into engine harness, then covered splice with heat shrink tubing before slipping wires back into split loom tubing.

This gives us a clean and secure connector to the sensor. This repair method can be used for many other connectors in the car.

Also installed a new retainer clip salvaged at the scrapyard to replace the one that was missing from this car. Now this connector will be secured instead of swimming around on its own.

Installed missing connector retainer.

Plugged connectors together and secured on “new” retaining clip.

Sprayed contact cleaner on new sockets before plugging connectors together to fight off corrosion.

Ran the the engine to normal operating temperatures and verified that the sensor is behaving. Checked ECT with new sensor at normal running temp and it now reads 196°.

New sensor reads hot stable temperature of 196°F. Was too low with old sensor.

Time will tell on this fix but I’m optimistic. Assume it solved the problem unless I report otherwise.

$37.88 for a cheap after-market ECT sensor. $10 for a sensor connector and retaining clip from a scrapped Volvo.

Technical Notes

The ECT sensor is a simple negative temperature coefficient thermistor. That means its resistance decreases with temperature.

The Volvo 850 uses the known resistance curve to determine temperature proportional to this resistance based on the voltage across this sensor. A pull-up resistor reference to +5V forms a voltage divider with the thermistor being the variable device.

ECT sensors are very important in the Volvo 850 (and most modern cars) because it is used for fuel trim, idle air, ignition timing and cooling fan operation.

ECT sensor resistance table per factory specs:

Resistance

7300 ohms at 32 deg F

2800 ohms at 68 deg F

1200 ohms at 104 deg F

300 ohms at 176 deg F

150 ohms at 212 deg F

From the factory functional description:

The Engine Coolant Temperature (ECT ) Sensor supplies the Engine Control Module (ECM ) with a signal describing the temperature of the engine coolant. This gives the engine coolant temperature (ECT) sensor a measurement of engine temperature and influences the control of:

Injection period

Idling speed

Engine Cooling Fan (FC )

Ignition timing

On-Board Diagnostic (OBD ) functions.

The sensor incorporates a temperature-sensitive resistance with a Negative Temperature Coefficient (NTC ). The sensor is supplied with a stabilized voltage of 5 V from the engine control module (ECM).

The voltage across the sensor is a function of the engine temperature and, therefore, of sensor resistance. Voltage can vary between 0 V and 5 V .

The engine control module (ECM) uses substitute values if the signal from the engine coolant temperature (ECT) sensor is missing or faulty, however, substitute values can cause starting problems in very cold weather.

The engine coolant temperature (ECT) sensor is mounted in the thermostat housing.

Had a recurring error code P0442 on my 850 sedan which indicates a small evaporative emissions leak. This is often due to the fuel filler cap not being tightened. In older cars with aged rubber it can be a cracked hose or elbow anywhere around the fuel tank or charcoal storage canister or evap purge valve. When the crack is big enough you get the large leak code P0455.

Finding these is hard. Professional shops often pressurize the fuel tank with some kind of non-incendiary smoke and look for where it might leak out. I don’t have that specialized equipment and I’d be a little nervous with it anyway. What I do have is a combustible gas detector that is rather sensitive. It is made to check for leaks on natural gas (methane) appliances but the operating principle is such that it will detect any combustible gas, which includes gasoline vapors.

I have this UEI CD100A combustible gas leak detector.

To prove the theory, I made a video showing it working as I crack open the fuel tank cap:

So you see how it can detect even small fuel vapor leaks. The probe is long and flexible so you can snake it into small, narrow places if needed. It doesn’t give an actual measurement but it will indicate a relative leak level.

Anyway, I used this technique to pinpoint a leak around the fuel pump. Gasket was not located properly and nut was not tightened adequately.

This unit is around $134 on Amazon. There are similar detectors on Amazon and generally on the internet. You can pay as much as $400 for them but I don’t see any doing a better job than this cheap one. It’s still a bit expensive but you can probably justify one if you have gas appliances in your home and you want to check for leaks periodically. Factor in the hourly rate of dealer shops for something like this and it may pay for itself in the long run with an older car that will have fuel vapor leaks.

Car was losing coolant at a rate where the coolant level warning light would come on once a month or two. Not a huge leak but concerned me enough to look into it before the situation got worse and maybe stranded the driver with a blown hose or overheated engine.

The leak was not enough to leave telltale drips on the ground so it wasn’t obvious what was leaking. I also didn’t want to run the engine to get hot fluid circulating if I was looking for leaks. The usual way to find a problem like this is to pressurize the cooling system with a special tester. I researched this and found a decent one at Harbor Freight Tools for maybe $55 with a coupon. Then I thought about rigging up my own tester to save money and thought I could get a new coolant reservoir cap and drill a hole in the old one and add an air pressure port to it and inflate with a bicycle tire pump or something. That might work but then I noticed that the brake fluid reservoir on the 850 appeared to have a cap of the same size and thread as the coolant reservoir. Those Swedish engineers are so clever! It is the same fitting and so I could use my brake fluid pump to pressurize the cooling system. Here it is connected to the coolant reservoir instead of the brake fluid reservoir where it is intended:

Motive Products power brake bleeder hooks up perfectly to the coolant reservoir.

I checked the pressure relief rating of the coolant cap and it shows 150kPa which is about 22psi.

Coolant reservoir pressure cap relieves at 150kPa (22psi).

So I pumped the cooling system up to 15psi and looked for leaks. Since there were leaks the pressure slowly dropped at a rate of about 5psi in 10 minutes (half psi per minute).

Pressurized cooling system to 15psi to make leaks more evident.

Checked around all hoses and fittings, the reservoir and radiator looking for signs of coolant. Any cracks or weak points will leak fluid when pressurized. I found a fresh wet spot below the upper radiator hose connection:

Small leak at upper radiator hose connection.

Hose seemed to be otherwise in decent condition so started by tightening the hose clamp. I tightened it about two turns and then cleaned up the fresh coolant to see if that made a difference.

Sure enough, no more fresh coolant leaking and the pressure loss rate dropped significantly to maybe 1psi in 20 minutes. That indicates there is still a tiny leak but this bigger one was taken care of. I expect the hoses will need to be replaced in a year or two but for now this should cut down quite a bit on the coolant loss.

Finding no other leaks under the hood I went looking for trouble under the passenger side of the dashboard where the heater core is located. Sure enough, after removing the lower cover I found a wet rusty spot and then more wet spots when I pulled the carpet back and removed the console side cover. This is consistent with the odor of antifreeze (ethylene glycol) when the heater is turned on (fortunately not often here in central Texas).

So that will be a separate topic because it’s a big project to replace the heater core. I’ll decide if and when on this later.

Well, with all my good intentions of getting a few more maintenance tasks accomplished soon, the weather and short days have minimized my time to look into things. This time of year it’s dark when I get home from work and often cold so weekends may be my only chance to get anything done.

Meanwhile, two new issues have cropped up which require more immediate attention (not to mention a recurring error code on my 850 sedan for an evap leak).

First is a mysterious coolant leak. The coolant level seems to drop fairly quickly with no signs of leaks on the ground and no steam out the exhaust so this will take some work to identify the problem. I hope it’s not an engine internal leak (head gasket) which would be most serious. It could be the heater core because I know it has at least a pinhole leak (I can smell antifreeze when the heater is on, but this is infrequent so may not be the main problem.) Hoping it’s just a cracked coolant bottle or radiator or hose which can be replaced fairly easily. Small enough not to notice a drip under the car but big enough to lose a liter or two in a month. Will report on this when I get it figured out.

Second is more troubling– intermittent engine stalling. Engine just dies when driving slowly; fortunately this hasn’t happened at high speeds when it could get hazardous. Car can usually be re-started right away. This could be many things from fuel problems to engine sensors/controls to ignition coil. Whatever it is, it’s intermittent and these are difficult to pin down and diagnose because you have to catch it in the act and there are many possibilities here. Very random problem once a week or two. Will also report on this. I don’t expect a fuel problem because I already replaced the pump and filter and repaired the pump relay.

Thought I’d share this excellent reference for Top 10 most common problems with the 850.

IPD published a list of the most common problems with this car model, presumably based on failure data. They mention ten items but the comments are also very helpful because dozens of readers mention other common problems and remedies.

This should be interesting and useful to all Volvo 850 owners. I agree with the list and the commenter’s additional high-failure items since I have seen many of these on this project car and my 850 sedan.

Interesting thing happens to this car when the engine is run very briefly. Scenario is to turn the cold engine on and move the car three to six feet (one or two meters), then quickly switch the car off.

This condition will sometimes result in it being very difficult to start the car next time. That is, the starter cranks hard and there is spark and fuel but no ignition; the engine simply won’t run on its own.

The explanation I have found on the web somewhere (and can’t locate this nugget of info again) is that when you run the car very briefly from a cold start it doesn’t give the engine controller time to adjust fuel air mixture and dumps extra fuel into the cylinders. So next time the engine tries to start the cylinders are already wet and you’re just adding more fuel. With the mixture so rich the wet plugs can’t ignite the fuel.

The solution which was suggested and which has worked for me a couple of times is to be patient and crank the starter for quite awhile, perhaps two minutes. Holding the throttle open with the accelerator pedal brings more air in and eventually the ratio will ignite and the engine starts to catch. It will soon run on its own although rough for a minute until things settle out. If your battery is weak in this condition you may need to use jumper cables from another car.

Well, this project car is back home for some time. Have hardly seen it since August when it went off to college. Will be here until late spring or early summer as the college driver will be studying overseas for a term.

That means we can get some more tasks worked on and you should see a little more activity here in the coming months.

Weather is cold here and money is tight so I probably won’t do very many expensive things but between the two 850s in the driveway I have several items to tackle.

There is a large plastic cover under the engine called an air guide. Its purpose is to protect the engine and also to help direct air flow for optimal engine cooling. This air guide is also known as the belly pan, splash pan, skid plate or lower engine cover.

Since many Volvos are missing this part, some people don’t think they need one, but Volvo put it there for a reason. Not only does it help guide air through the radiator, it also keeps water, dirt, gravel, rocks, wood, road grime, and debris off critical engine components like the alternator and belts.

Sometimes the air guide is removed for service and not replaced. Also because the 850 is so low to the ground in front, the air guide frequently scrapes against parking curbs and such. Eventually this will shear the plastic hangers and the air guide falls off. That’s what happened here. If you’re fortunate you will notice this and rescue the part. If the part is left behind you’ll need to get a new air guide, louver and clips.

Black tabs on left and right sides are all that secure the air guide to the car. When the guide shears off you have just the mounting tabs bolted to the chassis.

Broken tab on other side.

On this car we were able to recover the broken air guide so it was a simple matter of transferring the louver to the new air guide.

Old louver transferred to new air guide.

Old louver transferred to new air guide re-using side mounting clips.

New air guide with old louver ready to install on car.

While the air guide is secured to the car with bolts at the sides, there are features that help hold it in place loosely. Without these installing the air guide is difficult.

A line of clips at the front holds the guide on top of the front bumper ledge:

A slot at the bottom center of the radiator accepts the rear tab of the air guide:

Rear tab supported by slot in radiator.

Note that this radiator slot is frequently crushed by jacking or high curbs so may need some coaxing back into shape with pliers.

Supported in front on the bumper and back on the radiator, the air guide will stay in place where it can easily be secured with bolts at right and left:

When done it looks like this:

New air guide installed.

The round hole nearest this view is for radiator draining.

The Volvo diagrams show an additional smaller air guide piece that fits in or around the open rectangle. I have this part but haven’t figured out exactly how or where it goes because nothing makes sense with it. This main part should be all you need to protect your engine and improve air flow.

$17.98 Factory Replacement Air Guide (note shipping for this large item may be expensive, although with Volvo Parts Webstore it was not)

Not much activity lately as the car has been off to college since August. Had it home this weekend so was able to check the oil level. Favorable results to report with the thicker oil (15W-40) so I updated that post.

Also updated the post about lifting the car to add info and photos with ramps.

Nothing will get a forum stirred up like a discussion of engine oil. Lots of opinions on the topic, and many people strongly believe in certain types, brands and viscosities.

Regarding brand or type, I have no strong opinion and to split the difference between the synthetic oil vs. conventional oil crowds I went with a blend of the two at the posted oil change topic, and selected a name brand based on price and availability. When not changing the oil myself I usually have it done at Firestone where they use their own conventional/synthetic blend.

5W-30 installed at blog posted oil change.

Since then I have been mystified at the significant oil consumption of this car along with my daily driver, another 1997 Volvo 850 (sedan). Decent power and no tailpipe smoking but they seem to lose a quart every 1000 miles or less.

Pondering this I started researching oil consumption and type and realized that the 5W-30 is a bad choice for the 850 in this climate. Central Texas is relatively hot most of the year and rarely drops below freezing in winter. 5W-30 is intended for cold climates where normal oil will thicken at low temperatures. Here is a chart from the 1997 Volvo 850 owner’s manual:

Owner’s manual chart of viscosity range vs. ambient temperature.

It shows that the 5W-30 is fine for low temps (not needed here) but, worse, it is not recommended when used above 68°F (20°C) ambient, which we frequently exceed here. The problem with the low temp rating in higher ambient conditions is that the chemicals needed to make the oil flow when cold break down and form sludge. And as it breaks down there is less chemical to keep it thin at lower temps, so the cold rating becomes progressively weaker.

10W-30 would be a better choice, being commonly available, but even that is challenged by our high summer temps per the chart. 15W-40 seems ideal for my situation, based on min and max temperatures here. It’s not very common (more of a diesel engine oil) but I can find it at Walmart and auto parts stores plus at least one of the oil change places says they have it.

15W-40 is actually on the chart of permitted viscosities but there is a note in the manual cautioning the low end temperature range:

Not a problem here so I will be switching over to 15W-40 shortly and see if oil consumption drops off. Will add an update here as I learn if it helps or makes no difference in consumption.

Edit 29 September 2013: After switching to 15W-40 on both 850s I can report favorable behavior results. It’s been more than a month and oil consumption has dropped significantly. No smoke from the exhaust and the engine runs fine. Hardly notice the drop in oil level on the dipstick now where it was adding a quart every week or two before with thinner (5W-30) oil.

Tech Note

I’m no tribologist but I’ve done a bit of online research on this. Viscosity is a fluid’s resistance to flow. A single number (eg, SAE30) denotes oil viscosity at normal hot engine temperatures. The smaller the number the more quickly it flows, meaning it is thinner. Heavier oil flows more slowly and has a larger number. Ultimately you want a viscosity that is optimal for the car’s engine at operating temperatures, which is typically SAE 30 or 40 for the model 850.

A number with a W (for winter, such as 10W) means is behaves like a an SAE 10 rated oil at a low temperature. The lower the W number, the lower the temperature the oil will flow. So colder climates need lower W numbers when the engines are started up to have some lubrication until they warm up. These can be thought of as “thinner” oils until they get to engine operating temperatures when the second number becomes dominant.

The combination is called a multigrade oil and reveals the low temperature behavior and the normal high temperature behavior. So 5W-30 is a thinner 5 viscosity when cold but heavier 30 viscosity when warm.

In warm climates the low W numbers are too thin for old, worn engines so they get consumed faster than higher W numbers. I also expect that the older, worn engines can tolerate a higher warm viscosity as well, perhaps improving compression?

When the radiator shroud was removed to replace the front engine mount I noticed that the black plastic air duct which brings cooling air to the engine control unit (ECU) was cracked at the corrugated bellows.

Cracked air duct leaks air intended to cool ECU.

This cracks leaks air so that the ECU will get less cooling, a concern here in the hot climate of central Texas.

The part itself is not very expensive (~$10) but why replace when it can be easily repaired at little or no cost? The simple solution is to wrap black electrical tape around the cracked area. The tape is flexible to allow for movement and it is durable– the same repair has lasted for several years on my other 850.

A few wraps of electrical tape make for a quick and easy repair that lasts for years.

Some of our Volvo 850s have the optional remote keyless entry system installed which uses a small remote control typically attached to the car keys (key fob). This particular remote style (Volvo part # 9442982) is used on 850s in years 1996 and 1997 (the last two years before becoming S70/V70) along with a few other Volvo model numbers.

One weakness in the design is the flexible strap from the remote control module to the key ring. I have seen both leather and a vinyl-like plastic or rubber strip used for this and both will tear over time so they separate. If it’s a clean tear near the remote you may be able to punch another hole in the strip and re-attach it to the remote. After doing this a few times on three key fobs it became impossible to re-attach. So I devised a simple way to connect the key ring without the strap.

Basically you disassemble the remote by first removing the batteries. Then pry the two halves apart with a non-marring tool. A guitar pick works well for this.

Prying the remote apart. A guitar pick is very handy for this.

Inside you can break it down into a printed circuit board (PCB), buzzer and then a rubber pushbutton membrane. Taking all these out leaves you with the two black plastic halves of the remote housing.

What I do is carefully drill a hole in both halves where the strap retaining pin is (break the plastic post off first). The hole should be just larger than the key ring you want to attach. It can be fairly large before compromising the integrity of the plastic housing.

Holes drilled in each half of the remote.

Then re-assemble the key fob with all the parts in place and slip the key ring through the hole. It works well and you’ll never have them separate again.

Key fob ready for action again without breakable strap.

While we’re on the subject, there is one more little hint here regarding the buzzer. When you push the lock and unlock buttons there should be a slightly audible chirp from the remote. This is audible feedback that the remote sent out a lock/unlock signal; basically telling you that the battery and pushbuttons are working. If you don’t hear the chirp it means either that the remote is defective, the batteries are weak or dead, or that the buzzer is dislodged or otherwise does not have a good connection to the circuit board.

The buzzer touches two arms extending from the board and it sits in its own recess in the bottom half of the remote. It should be oriented as shown. If it doesn’t chirp with fresh batteries and is situated properly, the contacts may be corroded. Try scrubbing the buzzer surface with a pencil eraser, along with the metal contacting it. It should work with clean connections, fresh batteries and being properly installed.

We started this 1997 Volvo 850 wagon project a year and a half ago and so far the blog has exclusively detailed this particular car. I have documented 84 maintenance or repair items to date plus thrown in several posts on general topics or non-repair items. If it has a number, it is a repair or maintenance item. No number means general topic or improvement task or something along these lines.

Interest in this blog has grown quite a bit and we have followers around the world. In fact, this blog has really grown way beyond my original intent of letting my kids know what I’ve been doing to the car. The truly interested audience now are hundreds of fellow 850 owners looking for encouragement, advice or reference. If I can do it, you probably can, too.

Since we have tackled most of the main tasks on this project car, I think it’s time to start adding in a few things that I have done on my own daily driver, a 1997 850 sedan. This car is slightly different but still an 850 and such posts would be very relevant to the blog. Sure, there will still be several items in the future on the project car (it never ends, does it?) but don’t be surprised to see some posts featuring my other 850 now.

The other car in our driveway. You will see some posts involving this one in the future.

Besides the obvious color and body style differences they are much the same– age, mileage, normally aspirated (non-turbo). Differences are: the sedan has a manual transmission, sun roof, beige interior with wood dash and leather seats (electric). So for all practical intent, things that I do to the sedan could very well be tasks on the project car (in fact, many have been done to both cars.) And adding this in the mix makes it more helpful and relevant to an international audience.

This was a quick preventive maintenance task. Over time the flasher circuit can go bad in these cars and the turn signals or emergency blinkers will not work. This is sometimes due to a defective electrolytic capacitor in the flasher relay module located in the dash. I have seen discussions on 850 forums where the turn signals stopped because of bad capacitors so I wanted to be proactive and refresh them on this car before they did cause trouble.

The flasher module is removed by prying it out of the dashboard.

Pry carefully on sides/top with narrow tool and pull flasher module out of dash, then unplug connector.

To open the module the two lamps have to be removed first by twisting CCW.

Two lamps need to be removed before sliding board out of module.

Then the module is opened by prying up on both sides to free them from the locking tabs. A thin, sturdy guitar pick is particularly useful for this and I keep a few handy for opening electronic cases and car modules.

Carefully pry up on housing on both sides to release inner module. Guitar pick is particularly helpful.

There are four electrolytic capacitors on the printed circuit board. These are the four black cylinders shown.

Electrolytic capacitors are the four cylindrical shapes on the printed circuit board (PCB). Big rectangular object is the flasher relay which makes the clicking sound when it switches on and off.

Unsoldered all four capacitors and replaced with high quality replacements of same capacitance and voltage. Capacitance value and tolerance are the most important thing, along with temperature rating. It’s OK (actually, good) to replace with higher temperature and voltage ratings, but be aware that size increases with voltage rating. Component spacing is also important but you can often force-fit a physically larger part with wider pin spacing onto a PCB if needed.

New capacitors installed with old original parts in background. New parts slightly larger in size but fit with no problem.

After soldering in the new caps and clipping the leads I checked the circuit side for solder blobs or residue. Cleaned with alcohol and brush then re-assembled module. This is a good time to replace the two lamps, especially if one is out (the emergency flasher lamp probably has a lot of life left in it.)

Plugged the module back in the car and tested to make sure flashers and turn signals worked, then pushed the module back into the dash. Ready for another 15 years, hopefully.

Several modules in the Volvo 850 have circuit boards with electrolytic capacitors and the caps can cause problems for any of these modules as they age. For a detailed explanation of electrolytic capacitor function and failure, refer to the technical notes in item #54, fuel pump relay. If you’re handy with a soldering iron it’s an easy and economical fix for some of these fairly expensive modules.

Since we got this project car a year and a half ago it has bothered me that there is quite a bit of engine vibration in the car. This was made worse when I replaced the upper torque mount and lower transmission mounts with long-lasting but stiff polyurethane parts. At idle it’s not too bad but fairly strong when the automatic transmission is in the drive position (engine torque applied to wheels against brakes). This suggests that there is some engine twist towards the front of the car, even after I pre-loaded (tightened) the upper torque mount while in the drive position.

The Volvo 850 engine rests on three separate engine mounts which are in turn sitting on the engine sub-frame. There is a hard rubber mount below the crank pulley on the right hand side of the car, and this is a prime candidate for vibration when it wears down since it can allow the engine to directly touch the chassis. However, this mount appears to be in good shape upon visual inspection and you would expect constant vibration if this one failed (when idling and in drive.)

Besides the rigid mount on the RH side there are two large fluid-filled pads in the middle of the engine, one forward and one aft. Because these are filled with fluid they usually indicate failure by leaking their filling (some kind of hydraulic oil?) Without this fluid they are just shells of rubber which provide only weak support to the engine.

I suspect that the engine pad in the front of the car is bad. It’s not leaking but could have bled out years before we got the car. It appears somewhat collapsed since the safety cable surrounding it is somewhat relaxed.

Suspect engine pad located behind the radiator.

Replaced the front engine pad by unbolting it above and below, then lifting the engine with a jack to gain clearance to remove and replace the pad. The upper torque mount and lower transmission mount need to be removed to allow engine movement for this operation. Also the fan shroud is removed to gain space to unbolt the mount top nut and remove the pad.

Comparing old and new pads. Old pad slightly shorter and more impact was felt when struck against concrete.

New pad installed, top view.

New pad installed, side view.

After installing the new engine mount/pad, everything was put back together (torque mounts, fan shroud).

Fired the engine up and put the automatic transmission in drive with the brake on, the worst-case vibration situation. Unfortunately there is still significant vibration. It is slightly improved but I will need to look for the vibration problem somewhere else later– rear engine pad, hard mount, stiff torque mounts…

This post is for my new friend Donovan in South Africa. He made me realize that a basic task such as lifting the car is not obviously accomplished without the right equipment and instruction.

Much of the work done to the car is with wheels off or just to have clearance under the car to work. Proper lifting and support techniques are essential to minimize the chance of bodily injury or damage to the car.

If you have nothing else to raise the car, the emergency jack stowed inside the spare tire is your only tool at hand. This scissors-type jack is placed under a lift point and then the handle is cranked clockwise (CW) to raise the car and counter-clockwise (CCW) to lower it. When using the emergency jack, only the pre-defined jack points should be used. These are located in the body below the front doors, one on each side. These points are determined to be optimal to lift one side (left or right) equally, front to back. The locations are slightly forward of the mid-line since most of the weight is up front with the engine. Follow the instructions in the owner’s manual for jack usage.

Emergency jack in low position, ready to lift car.

Jack raised to maximum height.

Max lift equal front-rear. Jack is strong but not terribly stable so use care with emergency jack.

When working on the car in your garage, the car’s jack should be used only if a better jack is not available. This jack requires a lot of physical work and is not particularly stable. It has only minimal point of contact to the ground and to the car and it is narrow, meaning it is prone to having the car slip off the jack and crashing down.

When working on the car for maintenance or repair (non-emergency), a good hydraulic floor jack is a necessity. This type of jack is on wheels so it will automatically center under the lift point. It also spreads the load out over a wider area for excellent stability and it requires minimal physical exertion when raising and lowering the car.

Two typical sizes of hydraulic floor jacks, Small one rated for 3300 lbs with a 14″ lift. Large one rated for 4500 lbs with an 18″ lift (most useful).

Jack located at proper lift point.

Larger jack quickly gives good lift height.

Always support the car on stands after lifting with a jack. That means after the jack stands are carefully placed in position, lower the car to rest on the stands. After the car is resting on the stands, push the car hard with all your weight side to side AND front to back. This force will verify that the car is stable on the stands and that wind, a bump or tool force will not push the car off the stands while you are working underneath it.

Jack stand placement must be on reasonably firm, level ground under a solid, stable part of the car. For the front I use these points behind the wheels towards the centerline:

Good front jack stand location.

For the rear I use a point inside the wheels:

Good rear jack stand location.

When working on one side only (such as when rotating the tires front-rear/rear-front), raise the car at the designated lift point, then place stands front and rear and lower the car onto them.

When working under the front of the car only, you can lift the front once and place jack stands under both sides. A good lift point for a hydraulic jack is the front engine sub-frame, reasonably centered:

Front end lift point: engine sub-frame.

When using the single front lift point you can quickly get to this good working arrangement:

Lifted onto jack stands and ready for front end work underneath.

When working on the rear only, there is not a good single lift point so you’re stuck lifting one side at a time for placing jack stands.

Another safety consideration is to make sure the parking brake is set and that the wheels are blocked opposite the end that is being lifted. This prevents the car from shifting away from the jack and jack stands. These curved wedges are ideal but you can use anything that practically prevents the tires from rolling:

Both rear wheels chocked when front is lifted.

When working on the car with wheels on (oil change and under-engine work), ramps are another option. You simply drive up them to ramp height and the ramps provide extra clearance under the car to work. The down side to ramps on the 850 is that you need low-profile ramps to clear the low and long front end. This means practical lift is only about 8″ (200mm) and the car is already under 8″ to begin with. So with ramps you get less than 16″ (400mm) working room but this is manageable for most people, depending on the work and tool size/motion required.

850 front end is rather low and long, requiring shallow ramps.

I find that most of my work is wheels-off so I need the jack and stands anyway. But for oil changes and other wheels-on work ramps are convenient if you don’t need much clearance underneath. Shown below are ramps in action for an oil change on my white sedan.

Low profile ramps needed.

Drive car up ramps after carefully positioning them. Good to have a 2nd person to monitor when driving up.

After running very low on fuel the car would not start. The starter would crank and there was spark but the engine would not show any signs of ignition. After adding a gallon of gas it still would not start. I must have killed the pump by letting the fuel level drop too low since the electric pump sits in the bottom of the gas tank and is cooled by the liquid fuel. One too many times, I guess, and this was the episode that finally did it in.

I verified that the problem was fuel-related by a lack of pressure at the fuel rail on top of the engine and certain that the fuel pump relay was working. Further, I was able to temporarily get the pump running by banging on the fuel tank from under the car. Sometimes if they fail you can whack them into submission but this is a temporary fix only; it will not last so the pump has to be replaced.

Fortunately the fuel pump can be replaced without removing the fuel tank. There is an access plate inside the car (in the trunk/boot of Sedans and under the rear deck of wagons). Once this cover is removed the pump can be replaced from inside the car. Many of the same steps were involved in the fuel tank removal in item #57.

Fuel pump access beneath a cover under the rear deck.

Depressurized the fuel line (if the pump was fully dead there may not have been much pressure) at the Schrader valve near the fuel filter underneath.

Then disconnected the fuel lines by carefully prying up the slip-on fuel connectors (noted their position for re-connection). Unplugged the fuel pump connector so the unit was free to remove.

Unscrewed the big plastic locking ring holding the fuel pump to the fuel tank. This was done with large adjustable jaw oil filter pliers (the official Volvo method involves a special fuel pump spanner wrench.)

Oil filter pliers work well to turn the locking ring (giant plastic nut).

Note: At this point fuel can leak out of the tank, depending on how full it is. If you just filled up and the tank is overflowing up the filler pipe you may want to siphon fuel down below the top of the tank. The safest thing here would be to completely drain the fuel tank to minimize the hazard of fire or explosion. Also disconnect the car battery to eliminate one source of ignition should fuel vapors accumulate. Obviously, no smoking or open flames or sparky things while working with/around fuel.

After removing the locking ring, I lifted the pump out of the fuel tank and set aside to dry out for disposal or rebuilding.

Lifting the pump out of the fuel tank.

Drying the pump out in the sun.

I chose to rebuild the pump by replacing the pump component instead of replacing the whole pump assembly. This is much more economical; I bought a complete fuel pump service kit from FCP which includes the pump, new locking ring, strainer, wiring harness, fuel hose, gasket, plus a fuel filter and even a new fuel pump relay (which is good to have as a spare but I did not replace it since I just rebuilt it). All factory parts, not after market junk.

This took some time so while I was rebuilding the pump I covered the open fuel tank hole with aluminum foil to minimize vapors in the car on a hot day and reduce the chance of something falling down into the tank.

Covered the opening with foil while rebuilding the pump.

Update 4/9/14: As mentioned in a follow-up post, if the locking collar (nut) securing the pump is to be off for more than a half hour, thread it back on to the fuel tank. This prevents swelling of the tank port which will make it difficult to put the nut back on later.

Rebuilt the pump assembly indoors (hot day so the air conditioned house was a blessing!) by replacing the pump component and a new strainer. This involved separating the inner and outer housings and loosening the supply hose.

New parts shown outside original pump assembly.

Assembly separated with old and new pumps for comparison.

New pump is shorter with smaller diameter. Foam sleeve around new pump makes it fit in housing.

New pump installed in lower housing, ready to re-assemble into upper housing.

Re-assembled rebuilt pump. Female disconnect terminals match original pump and they are sized differently so no possibility of reverse polarity.

Replaced original gasket which was hardened and stiff with new one supplied with kit. Added some silicone grease to gasket for better seal on top of tank.

Installed filter sock to bottom of pump in proper orientation.

Installed the renewed assembly back in the fuel tank with a new locking ring provided with kit. Tightened locking ring just past hand tight. Plugged wiring connector back in and pushed hose fittings back on.

Checked for leaks with engine running to make sure there were no surprises. Then tested by driving the car at high speed to make sure the rebuilt pump was working well before I put the cover and decking back on.

Ran the car and then drove it before re-installing covers over pump.

Post-mortem exam revealed that the original pump motor had an open coil, consistent with overheating. Good pump motor coil reads about 1.5 ohms on a multimeter; this one was infinite (open circuit).

Moral of the story here is: To preserve the life of an in-tank fuel pump (on any car, not just the Volvo 850), don’t let the fuel level drop too low, at least not very often. Lacking proper cooling from the gasoline can cause the pump motor to overheat and fail. I have heard professional mechanics say you should re-fill when down to 1/3 tank; probably good advice.